Which of the following is not a function of the trachea?
a. provide a pathway for air to enter the lungs.
b. provide a pathway for air to exit the lungs trap dust and debris to prevent it from entering the lungs.
c. prevent food from entering the lungs.

The correct option is: c.prevent food from entering the lungs

Explanation:

Trachea is a cylindrical cartilaginous hollow pipe that branches into the two primary bronchi of the lungs. It is the passage of air that connects the larynx to the lungs and thus it is also known as the windpipe.

The trachea is lined with a mucous-membrane which moistens and protect the airway. It also traps and prevents the dust and other contaminating particles from reaching the lungs.

a covalent bond, specfically triple bond