What is the function of cilia in the nasal passages?

Cilia in the nasal passages play a crucial role in filtering and trapping particles that enter the respiratory system. These tiny hair-like structures line the nasal cavity and are part of the respiratory epithelium. They work by moving in a coordinated, wave-like motion that helps to sweep mucus, along with trapped dust, pathogens, and other harmful particles, towards the throat. This mechanism is essential for keeping the airways clear and protecting the lungs from irritants and infections.

The other options relate to different functions that are not primarily associated with cilia in the nasal passages. Increasing surface area for taste is related to the structure of the tongue, while moistening inhaled air is primarily a function of mucus and the blood supply in the nasal passages. Sound production is more related to the larynx and vocal cords than the function of cilia in the nasal area. Thus, the correct answer highlights the vital protective role that cilia play in maintaining respiratory health.