Which of the following describes the function of mucus in the nasal cavity?

Mucus in the nasal cavity plays a crucial role in the respiratory system, primarily through its ability to trap small particles and pathogens. It is produced by goblet cells and mucous glands lining the nasal passages. When air is inhaled, mucus acts as a sticky barrier that captures dust, pollen, smoke, and microorganisms such as bacteria and viruses. This helps prevent these potentially harmful particles from entering the lungs and causing infection or irritation.

The other roles mentioned in the other options are either secondary functions or do not primarily align with the function of mucus in the nasal cavity. For instance, while mucus does aid in warming and humidifying incoming air, the primary description of its function related to trapping harmful substances makes the second option the most accurate choice.