Transplantation of tissues/organs often fails due to non-acceptance by the patient's body. Which type of immune response is responsible for such rejections?

Given below are two statements:
Statement $I:$ Autoimmune disorder is a condition where the body's defense mechanism recognizes its own cells as foreign bodies.
Statement $II:$ Rheumatoid arthritis is a condition where the body does not attack self-cells.
In the light of the above statements,choose the most appropriate answer from the options given below:

The spleen is a large bean-shaped organ which primarily acts as a filter of the blood by trapping blood-borne microorganisms. Which of the following statements is correct regarding the spleen?

Before and after organ transplantation,it is necessary to perform:

What percentage of lymphoid tissue in the human body is constituted by Mucosa-Associated Lymphoid Tissue $(MALT)$ (in $\%$)?

Identify the $APC$ (Antigen Presenting Cell) from the following.