The bronchioles do not collapse even when they are empty. What is the reason for this?

The inner wall of the pulmonary alveoli is composed of which type of epithelium?

The covering of the lungs in humans is known as....

The thyroid is a cartilaginous plate in:

What is the function of ciliated epithelium in the trachea?

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.