Which of the following is used as a unique and characteristic feature of the mammalian body?

The correct sequence of the air passage in humans is:

Diaphragm is found in

During swallowing,the glottis can be covered by a thin elastic cartilaginous flap called $A$ to prevent the entry of food into the larynx. The trachea is a straight tube extending up to the $B$ cavity,which divides at the level of the $5^{th}$ thoracic vertebra into right and left primary $C$. Choose the correct option for $A, B$,and $C$ from the given four options to complete the above statement with reference to the $NCERT$ textbook.

Two friends are eating together at a dining table. One of them suddenly starts coughing while swallowing food. This coughing action is likely due to the improper movement of the .......... .

The lungs contain a large number of narrow tubes known as: