Question

which statement(s) about the functions of the paranasal sinuses is/are not true? they make skull bones lighter. the mucus they secrete enters the oral cavities. they provide an extensive area of mucous epithelium. they are a potential site of infection. they support cilia that move the mucus.

Explanation:

The mucus secreted by the paranasal sinuses drains into the nasal cavities, not the oral cavities. Paranasal sinuses do make skull - bones lighter, provide an extensive area of mucous epithelium, are a potential site of infection, and support cilia for mucus movement.

Answer:

The mucus they secrete enters the oral cavities.