Epithelial tissue Questions in English

(D) Epithelial tissue is characterized by having a free surface,which faces either a body fluid or the outside environment.
This tissue provides a covering or a lining for some part of the body.
Specialized modifications of the plasma membrane on the free surface,such as cilia (for moving particles or mucus) or microvilli (for increasing surface area for absorption),are commonly found in epithelial cells.
Neural,muscular,and connective tissues do not possess a free surface as their primary structural characteristic.

(A) The walls of blood vessels and the air sacs (alveoli) of the lungs are lined by a single thin layer of flattened cells with irregular boundaries. This type of epithelium is known as $Squamous$ epithelium. It is primarily involved in functions like forming a diffusion boundary.

$(C)$ Compound epithelium is composed of more than one layer of cells (multi-layered), which makes statement $(I)$ correct.
Due to its multi-layered structure, it has a limited role in secretion and absorption compared to simple epithelium, making statement $(II)$ correct.
The primary function of compound epithelium is to provide protection against chemical and mechanical stresses, making statement $(III)$ correct.
Statement $(IV)$ is incorrect because $PCT$ (Proximal Convoluted Tubule) is lined by simple cuboidal brush-bordered epithelium, not compound epithelium.
Therefore, statements $(I, II, \text{and } III)$ are correct.

(B) Gap junctions are specialized intercellular connections that directly connect the cytoplasm of two cells.
This allows for the rapid transfer of ions,small molecules,and sometimes large molecules between adjacent cells.
They play a crucial role in cell-to-cell communication,allowing tissues to function as a coordinated unit.
Option $A$ describes tight junctions,which prevent leakage.
Option $C$ describes adhering junctions,which cement cells together.

(B) The correct matches are as follows:
$1$. $P$ (Cartilage) is found in the limbs (e.g.,hyaline cartilage in long bones).
$2$. $Q$ (Cuboidal epithelium) is found in the $PCT$ (Proximal Convoluted Tubule) of the nephron.
$3$. $R$ (Compound epithelium) provides protection against chemical and mechanical stresses and is found in the pharynx.
$4$. $S$ (Ciliated epithelium) is found in the bronchioles to move mucus.
Therefore,the correct sequence is $P-3, Q-1, R-4, S-2$.

(D) Compound epithelium is made of more than one layer (multi-layered) of cells and thus has a limited role in secretion and absorption.
Its main function is to provide protection against chemical and mechanical stresses.
It covers the dry surface of the skin,the moist surface of the buccal cavity,pharynx,inner lining of ducts of salivary glands,and of pancreatic ducts.
Option $D$ is incorrect because the secretion of substances like modified polysaccharides is primarily a characteristic of glandular epithelium,not compound epithelium.

(D) The provided figure shows specialized epithelial cells that are modified for secretion.
These cells are organized into structures that resemble glands,specifically goblet cells within an epithelial layer.
This type of tissue is classified as glandular epithelium,which is responsible for the secretion of substances like mucus.
Therefore,the correct identification is glandular epithelium.

(B) The primary functions of epithelial tissue include protection,secretion,excretion,absorption,and sensory reception.
Connection is the primary function of connective tissue,which binds,supports,and protects other tissues and organs in the body.
Therefore,connection is not a function of epithelial tissue.

(A) tissue is defined as a group of cells along with their intercellular substances that perform a specific function.
In multicellular organisms,cells are organized into tissues to perform complex tasks efficiently.
Option $A$ correctly describes this biological definition.
Option $B$ is incorrect because a tissue is a group of cells,not a single cell.
Option $C$ describes a specific type of epithelium (simple cuboidal),not the general definition of a tissue.
Option $D$ is incorrect because cells in a tissue typically perform a common or coordinated function.

(A) The epithelial cells described as thin,flat,and tile-like are known as $Squamous$ $Epithelium$.
These cells are found in the walls of blood vessels and air sacs of lungs,and they also form the inner lining of the cheek (buccal cavity).
Therefore,the correct option is $A$.

(D) The basement membrane is a thin,fibrous,extracellular matrix of tissue that separates the lining of an internal or external body surface from underlying connective tissue.
It is not composed of cells itself.
Instead,it is a specialized extracellular matrix secreted by the epithelial cells (basal lamina) and the underlying connective tissue cells (reticular lamina).
Therefore,it is a product of epithelial cells and connective tissue cells,rather than being composed of the cells themselves.

(A) The germinal epithelium is the layer of cells that lines the gonads (testes and ovaries) and is responsible for the production of gametes.
It is composed of a single layer of cuboidal epithelial cells.
Therefore,the germinal epithelium is a specialized form of cuboidal epithelium.

(B) Simple epithelial tissue is composed of a single layer of cells that are directly cemented to each other. These cells rest on a basement membrane and function as a lining for body cavities,ducts,and tubes. Because they form a single,continuous layer,they are specialized for absorption,secretion,and filtration.

(A) Cellular junctions are specialized structures that provide structural and functional links between individual cells.
These are primarily found in epithelial tissues,where cells are closely packed with little intercellular matrix.
Among the given options,ciliated epithelium is a type of epithelial tissue.
Epithelial cells are characterized by the presence of tight,adhering,and gap junctions that facilitate communication and adhesion between cells.
Thrombocytes (platelets) are blood cells,tendons are connective tissues,and hyaline cartilage is a specialized connective tissue,none of which exhibit the characteristic cellular junctions found in epithelial tissues.

(C) Cellular junctions are specialized structures that provide both structural and functional links between individual cells.
In $Epithelial$ $tissue$, cells are compactly packed with little intercellular matrix.
To provide structural integrity and facilitate communication, these cells possess specialized junctions:
$1$. $Tight$ $junctions$: Help to stop substances from leaking across a tissue.
$2$. $Adhering$ $junctions$: Perform cementing to keep neighboring cells together.
$3$. $Gap$ $junctions$: Facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells, for rapid transfer of ions, small molecules, and sometimes big molecules.
Therefore, these junctions are characteristic features of $Epithelial$ $tissue$.

(D) The inner lining of blood vessels, heart, and lymphatic vessels is composed of a single thin layer of flattened cells with irregular boundaries.
This type of epithelium is known as the $Squamous$ $epithelium$.
Specifically, it is referred to as the $endothelium$ when it lines the blood vessels.
$Squamous$ $epithelium$ is involved in functions like forming a diffusion boundary.

(A) Ciliated epithelium consists of cells that bear cilia on their free surface.
These cilia move particles or mucus in a specific direction over the epithelium.
In humans,ciliated columnar epithelium is primarily found in the inner surface of hollow organs like the bronchioles (respiratory tract) and the fallopian tubes (oviducts) of the female reproductive system.
Therefore,the correct option is $A$.

(C) The correct match is $C$.
$1$. Ducts of salivary glands are lined by cuboidal epithelium.
$2$. The moist surface of the buccal cavity is lined by non-keratinized stratified squamous epithelium.
$3$. Parts of the nephron (tubular parts) are lined by cuboidal epithelium,which helps in absorption and secretion.
$4$. The inner lining of bronchioles is lined by ciliated epithelium to move mucus and trapped particles.

(C) Gap junctions are specialized intercellular connections that directly connect the cytoplasm of two cells.
This allows for the rapid transfer of ions,small molecules,and sometimes large molecules between adjacent cells.
They play a crucial role in cell-to-cell communication and coordination of activities in tissues like cardiac muscle and smooth muscle.
Therefore,option $C$ is the correct answer.

(C) The ability of cells to regenerate depends on their capacity to divide.
$1$. Hepatocytes (liver cells) have a high regenerative capacity and can divide to replace damaged tissue.
$2$. The Malpighian layer (stratum basale) of the skin contains stem cells that continuously divide to replace dead skin cells.
$3$. Neurons and auditory hair cells are highly specialized cells that lose their ability to divide after development,meaning they cannot be replaced if destroyed.
Given the options,both Hepatocytes and the Malpighian layer are capable of regeneration. However,in the context of standard biology questions regarding tissue replacement,the Malpighian layer of the skin is the most classic example of continuous cell renewal. If the question implies a single best answer,the Malpighian layer is the most accurate choice for constant turnover.

(D) Ciliated epithelium consists of cells that bear cilia on their free surfaces. The function of these cilia is to move particles or mucus in a specific direction over the epithelium. In humans,ciliated epithelial cells are primarily found in the inner surface of hollow organs like the bronchioles and the Fallopian tubes. In the bronchioles,they help in moving mucus and trapped dust particles out of the respiratory tract,while in the Fallopian tubes,they assist in the movement of the ovum towards the uterus.

(C) Ciliated epithelium consists of cells that possess fine hair-like outgrowths called cilia on their free surfaces.
This type of epithelium lines the inner surface of hollow organs like the fallopian tubes (oviducts),bronchioles,and small bronchi.
The primary function of these cilia is to move particles,mucus,or cells (like the ovum) in a specific direction.
Squamous epithelium is found in the walls of blood vessels and air sacs of lungs.
Columnar epithelium lines the stomach and intestines.
Cuboidal epithelium is found in kidney tubules and glandular ducts.

(D) Cell junctions are specialized structures that provide structural and functional links between cells.
In animal tissues,three main types of cell junctions are found: $1$. Tight junctions,which prevent substances from leaking across a tissue; $2$. Adhering junctions,which perform cementing to keep neighboring cells together; and $3$. Gap junctions,which facilitate communication between cells by connecting the cytoplasm of adjacent cells.
Plasmodesmata are microscopic channels that traverse the cell walls of plant cells and some algal cells,enabling transport and communication between them. They are not found in animal cells because animal cells lack cell walls.

(D) Statement $(i)$ is true: Epithelial cells are compactly packed with very little intercellular matrix.
Statement $(ii)$ is true: Specialized junctions are present in animal tissues to provide structural and functional links.
Statement $(iii)$ is true: Tight junctions prevent substances from leaking across a tissue.
Statement $(iv)$ is true: Adhering junctions perform cementing to keep neighbouring cells together.
Statement $(v)$ is true: Gap junctions facilitate communication between cells by connecting the cytoplasm of adjacent cells for the rapid transfer of ions,small molecules,and sometimes big molecules.
Since all the given statements are correct,none of them are false.

(A) The squamous epithelium is composed of a single thin layer of flattened cells with irregular boundaries,which is a correct description of its structure. This structure is ideal for diffusion,which is why it is found in the walls of blood vessels (endothelium) and air sacs of lungs (alveoli). Since the structure (Assertion) directly facilitates the function and location (Reason),the Reason is the correct explanation of the Assertion. Therefore,both are correct and the Reason explains the Assertion.

(C) The correct matching is as follows:
$(a)$ Tight junctions: (iii) Establish a barrier to prevent leakage of fluid across epithelial cells.
$(b)$ Adhering junctions: $(i)$ Cement neighbouring cells together to form a sheet.
$(c)$ Gap junctions: (iv) Cytoplasmic channels to facilitate communication between adjacent cells.
$(d)$ Synaptic junctions: (ii) Transmit information through chemicals to other cells.
Therefore,the correct sequence is $(a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)$.

(N/A) Epithelial tissue lines the surface of a body and forms a protective covering. Epithelial cells are packed tightly together with little intercellular matrix. Epithelial tissue in the body is of two types.
$(a)$ Simple epithelium: It consists of a single layer of cells where cells are in direct contact with the basement membrane. It is further sub-divided into the following types:
$(i)$ Simple squamous epithelium: It consists of a single layer of flat cells with irregular boundaries. It is found in the walls of the blood vessels and in the lining of alveoli.
$(ii)$ Simple cuboidal epithelium: It consists of a single layer of cube-like cells. It is present in regions where secretion and absorption of substances takes place such as the proximal convoluted tubule region of the nephron.
$(iii)$ Simple columnar epithelium: It consists of a single layer of tall,slender cells with their nuclei present at the base of the cells. They may bear microvilli on the free surfaces. Columnar epithelium forms the lining of the stomach and intestines,and is involved in the function of secretion and absorption.
$(iv)$ Ciliated epithelium: It consists of columnar or cuboidal cells with cilia on their free surfaces. They are present in bronchioles and oviducts from where they direct mucus and eggs in specific directions.
$(v)$ Glandular epithelium: It consists of columnar or cuboidal cells involved in the secretion of substances. Glands are of two types,unicellular glands (goblet cells of the alimentary canal) and multicellular glands (salivary glands). They can be classified as exocrine (glands with ducts) and endocrine glands (ductless glands) based on the method through which they release their products.
$(b)$ Compound epithelium: It consists of many layers of cells. It is involved mainly in the function of providing protection and has a limited role in secretion and absorption. Examples of compound epithelium include the dry surface of the skin,the moist inner lining of the buccal cavity,pharynx,and the inner lining of ducts of salivary glands.

(N/A)

Simple epithelium	Compound epithelium
$(1)$ It is composed of only one layer of cells.	$(1)$ It is composed of many layers of cells.
$(2)$ It is mainly involved in the function of absorption and secretion.	$(2)$ It is mainly involved in the function of protection and has a limited role in absorption and secretion.
$(3)$ It is present in the lining of the stomach and intestine.	$(3)$ It is present in the lining of the pharynx and buccal cavity.

(B) Ciliated epithelium is a type of epithelial tissue that consists of simple columnar or cuboidal cells with hair-like projections called cilia on their free surfaces.
It is primarily found on the inner surface of hollow organs like the bronchioles (in the respiratory tract) and the oviducts (Fallopian tubes).
Its main function is to move particles or mucus in a specific direction over the epithelial surface.

(N/A)

Simple glands	Compound glands
$(1)$ They contain isolated glandular cells.	$(1)$ They contain a cluster of secretory cells.
$(2)$ They are unicellular.	$(2)$ They are multicellular.
$(3)$ Example: Goblet cells of the alimentary canal.	$(3)$ Example: Salivary glands.

(A) $\Rightarrow$ Based on the function of cells,there are four types of tissues found in animals: $(i)$ Epithelial,$(ii)$ Connective,$(iii)$ Muscular,and $(iv)$ Neural.
$\Rightarrow$ Epithelial tissue is commonly referred to as epithelium. This tissue has a free surface,which faces either a body fluid or the outside environment,thus providing a covering or a lining for some part of the body. The cells are compactly packed with little intercellular matrix.
$\Rightarrow$ Epithelial tissues are of two types: $(1)$ Simple epithelium,$(2)$ Compound epithelium.
$\Rightarrow$ Simple epithelium is composed of a single layer of cells and functions as a lining for body cavities,ducts,and tubes.
$(1)$ Simple epithelium: Based on the structural modification of the cells,simple epithelium is further divided into three types: $(a)$ Squamous,$(b)$ Cuboidal,$(c)$ Columnar.
$(a)$ Squamous epithelium: It is made up of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary.
$(b)$ Cuboidal epithelium: This tissue is made up of a single layer of cube-like cells. It is commonly found in ducts of glands and tubular parts of nephrons in kidneys and its main functions are secretion and absorption.
$(c)$ Columnar epithelium: It is composed of a single layer of tall and slender cells. Their nuclei are located at the base. They are found in the lining of the stomach and intestine and help in absorption and secretion.
$\Rightarrow$ Ciliated epithelium: If the columnar or cuboidal cells bear cilia on their free surface,they are called ciliated epithelium. Their function is to move particles or mucus in a specific direction over the epithelium. They are mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.
$\Rightarrow$ Glandular epithelium: Some of the columnar or cuboidal cells get specialized for secretion and are called Glandular Epithelium. They are mainly of two types: $(i)$ Unicellular (e.g.,goblet cells of the alimentary canal) and $(ii)$ Multicellular (e.g.,salivary gland). Based on the mode of pouring their secretions,glands are divided into $(i)$ Exocrine (with ducts) and $(ii)$ Endocrine (ductless) glands.
$(2)$ Compound epithelium: It is made up of more than one layer (multi-layered) of cells and thus has a limited role in secretion and absorption. Its main function is to provide protection against chemical and mechanical stresses. It covers the dry surface of the skin,the moist surface of the buccal cavity,pharynx,inner lining of ducts of salivary glands,and of pancreatic ducts.
$\Rightarrow$ Cell Junctions: All cells in epithelium are held together with little intercellular material. Specialized junctions provide both structural and functional links between its individual cells: $(i)$ Tight junctions (help to stop substances from leaking across a tissue),$(ii)$ Adhering junctions (perform cementing to keep neighboring cells together),and $(iii)$ Gap junctions (facilitate the cells to communicate with each other by connecting the cytoplasm of adjoining cells for rapid transfer of ions,small molecules,and sometimes big molecules).

(N/A) $\rightarrow$ It is composed of a single thin layer of flattened cells with irregular boundaries.
$\rightarrow$ The cells are arranged like tiles on a floor.
$\rightarrow$ They are held together by intercellular cement material.
$\rightarrow$ The cells are typically hexagonal in shape and possess a prominent nucleus in the center.
$\rightarrow$ The primary function of this tissue is to form a diffusion boundary and protect underlying tissues.

(N/A) $\rightarrow$ This tissue is composed of a single layer of cube-like cells. Each cell possesses a centrally located,spherical nucleus.
$\rightarrow$ The cells of this tissue sometimes have microvilli on the free surface to increase the area for absorption,for example,in the proximal convoluted tubule of the nephron.
$\rightarrow$ Location: This tissue is commonly found in the ducts of glands and the tubular parts of nephrons in the kidneys.
$\rightarrow$ In the ovary and testis,these cells are referred to as germinal epithelium.
$\rightarrow$ Function: These cells participate in processes such as secretion (e.g.,gastric juice and intestinal juice),excretion,and absorption.

(N/A) $\rightarrow$ The columnar epithelium is composed of a single layer of tall and slender cells. Their nuclei are located at the base.
$\rightarrow$ The free surface may have microvilli.
$\rightarrow$ Their inner ends are narrow,and the free ends are broad and polygonal.
$\rightarrow$ Location: They are found in the lining of the stomach and intestine.
$\rightarrow$ Function: They help in absorption and secretion.

(N/A) $\Rightarrow$ Glandular epithelium: Some of the columnar or cuboidal cells get specialized for secretion and are called Glandular Epithelium.
$\Rightarrow$ They are mainly of two types based on the number of cells:
$(i)$ Unicellular glandular epithelium: It consists of isolated glandular cells (e.g., goblet cells of the alimentary canal).
$(ii)$ Multicellular glandular epithelium: It consists of a cluster of cells (e.g., salivary gland).
$\Rightarrow$ On the basis of the mode of pouring of their secretions, glands are divided into two categories:
$(i)$ Exocrine glands: These glands secrete mucus, saliva, earwax, oil, milk, digestive enzymes, and other cell products. These products are released through ducts or tubes.
$(ii)$ Endocrine glands: These glands do not have ducts. Their products, called hormones, are secreted directly into the fluid bathing the gland.

(N/A) $\rightarrow$ Location: This tissue is found in areas subject to wear and tear,such as the dry surface of the skin,the lining of the rectum,buccal cavity,tongue,pharynx,salivary glands,esophagus,and the vagina of mammals.
$\rightarrow$ Function: It has a limited role in secretion and absorption. Its primary function is to provide protection against chemical and mechanical stress.

(N/A)

Simple Epithelium	Compound Epithelium
$(1)$ Cells are arranged in a single layer.	$(1)$ Cells are arranged in multiple layers.
$(2)$ It lacks a Malpighian layer.	$(2)$ It possesses a Malpighian layer.
$(3)$ Cells generally do not possess the property of active division for regeneration.	$(3)$ Cells possess the property of active division for regeneration.
$(4)$ Includes squamous,cuboidal,columnar,and pseudostratified epithelium.	$(4)$ Includes stratified and transitional epithelium.

(N/A) $(i)$ Squamous Epithelium:
Location: Found in the walls of blood vessels and air sacs of lungs.
Function: Forms a diffusion boundary.
$(ii)$ Cuboidal Epithelium:
Location: Found in the ducts of glands and tubular parts of nephrons in kidneys.
Function: Secretion and absorption.

(N/A) $(i)$ Location: The Malpighian layer (stratum germinativum) is the deepest basal layer of the epidermis in stratified squamous epithelium.
$\Rightarrow$ Function: The cells in this layer divide continuously by mitosis to produce new cells,which replace the worn-out cells of the outer layers,thereby facilitating tissue repair and regeneration.
$(ii)$ Location: Adipose tissue is primarily found beneath the skin (subcutaneous layer),around internal organs,and in the bone marrow.
$\Rightarrow$ Function: It acts as an energy reservoir,provides cushioning for organs,and functions as an insulating layer to maintain body heat.

(N/A) $(i)$ Ciliated Epithelium:
Location: Inner surface of hollow organs like bronchioles,fallopian tubes,and brain ventricles.
Function: To move particles or mucus in a specific direction over the epithelial surface.
$(ii)$ Stratified Epithelium (specifically Stratified Squamous):
Location: Skin (epidermis),lining of the mouth cavity,pharynx,and esophagus.
Function: Provides protection against chemical and mechanical stress (abrasion).

(N/A) $\Rightarrow$ Stratified epithelium consists of multiple layers of cells. Its basal layer is composed of columnar or cuboidal cells.
$\Rightarrow$ It is a type of compound epithelium,and its outer layer often contains a water-resistant protein called keratin.
$\Rightarrow$ The outermost layer consists of dead cells,which are shed during wear and tear. Due to this multi-layered structure,their function is limited in absorption and secretion.
$\Rightarrow$ The primary function of stratified epithelium in the skin is to provide protection to the body against mechanical and chemical stress.

$(A-1, B-2, C-3)$ Simple columnar epithelium: This epithelium forms the inner lining of the stomach, intestine, and gallbladder. It forms stomach glands and intestinal glands, where it functions in secretion. Therefore, it is called glandular epithelium. This epithelium has villi in the mucous layer of the intestine, which increases the absorption surface area; hence, it is called brush-bordered columnar epithelium.
$(B)$ Stratified epithelium: It is composed of epithelial cells arranged in more than one layer. It is also known as compound epithelium. Its lowermost layer, situated on the basement membrane, is adapted to withstand wear and tear. Hence, it primarily functions as a protective epithelium.
$(C)$ Connective tissue: This tissue functions to link various tissues or organs and to support various structures of the animal body. It originates from the mesoderm and consists of living cells embedded in an extracellular matrix, e.g., blood is a fluid connective tissue.

(N/A) Epithelial tissue is classified into two main types based on the number of cell layers:
$1$. Simple Epithelium: Composed of a single layer of cells,functioning as a lining for body cavities,ducts,and tubes.
- Squamous Epithelium: Made of a single thin layer of flattened cells with irregular boundaries. Found in the walls of blood vessels and air sacs of lungs. Function: Diffusion boundary.
- Cuboidal Epithelium: Composed of a single layer of cube-like cells. Found in ducts of glands and tubular parts of nephrons in kidneys. Function: Secretion and absorption.
- Columnar Epithelium: Composed of a single layer of tall and slender cells. Nuclei are located at the base. Found in the lining of the stomach and intestine. Function: Secretion and absorption.
- Ciliated Epithelium: If columnar or cuboidal cells bear cilia on their free surface,they are called ciliated epithelium. Found in the inner surface of hollow organs like bronchioles and fallopian tubes. Function: To move particles or mucus in a specific direction.
- Glandular Epithelium: Some columnar or cuboidal cells get specialized for secretion. They are unicellular (e.g.,goblet cells) or multicellular (e.g.,salivary gland).
$2$. Compound Epithelium: Made of more than one layer (multi-layered) of cells and thus has a limited role in secretion and absorption. Their main function is to provide protection against chemical and mechanical stresses. They cover the dry surface of the skin,the moist surface of the buccal cavity,pharynx,inner lining of ducts of salivary glands,and pancreatic ducts.

(C) The proximal convoluted tubule $(PCT)$ of the nephron is lined by simple cuboidal brush border epithelium. The brush border is formed by microvilli,which significantly increase the surface area for the reabsorption of essential substances like glucose,amino acids,and water from the filtrate.

(B) Goblet cells are specialized glandular cells found in the lining of the alimentary canal.
These cells are modified from columnar epithelial cells.
Their primary function is to secrete mucus,which lubricates and protects the lining of the digestive tract.

(A) The given diagram shows a single layer of cube-like cells,which is characteristic of simple cuboidal epithelium.
This tissue is primarily found in ducts of glands and tubular parts of nephrons in kidneys.
Its main functions are secretion and absorption.

(A) The given diagram shows glandular epithelium.
Some of the columnar or cuboidal cells get specialized for secretion and are called glandular epithelium.
They are mainly of two types: unicellular,consisting of isolated glandular cells (like goblet cells of the alimentary canal),and multicellular,consisting of a cluster of cells (like salivary gland).

(C) The provided diagram shows a tissue composed of multiple layers of cells,which is characteristic of compound epithelium.
Compound epithelium is made of more than one layer (multi-layered) of cells and thus has a limited role in secretion and absorption.
Its main function is to provide protection against chemical and mechanical stresses.

(A) tissue is defined as a group of cells that have a common embryonic origin and perform a specific,similar function. In multicellular organisms,these cells work together to carry out specialized tasks.

(C) Epithelial tissue covers the body surface or lines the body cavities.
The cells rest upon a non-cellular basement membrane,which is secreted by the epithelial cells themselves.
Epithelial tissue is avascular,meaning it lacks its own blood supply and receives nutrients via diffusion from the underlying connective tissue.