What is the length and diameter of the trachea?

Choose the incorrect statement.

Which of the following organs is not located in the thoracic cavity?

The much developed larynx of a human male is called:

$A$ fluid-filled double-membranous layer surrounds the lungs. Name it and mention its important function.

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.