Which statement is not true of cilia in the respiratory tract?
a. they clean the respiratory system.
b. they are thin structures that resemble hairs.
c. they close the windpipe opening when swallowing.
d. they move mucus from the bronchi to the pharynx.

The answer is letter C.They close the windpipe opening when swallowing. This function is done by the epiglottis. It keeps the windpipe safe by closing it and trackingthat the food comes in the right pipe which is the pharynx that is connected to the esophagus.