Which of the following protective mechanisms helps to trap and expel pathogens from the respiratory tract?

Coughing and sneezing serve as critical protective mechanisms for the respiratory tract by acting as reflex actions that help to clear irritants, pathogens, and foreign particles. When the respiratory system detects an inhaled irritant or pathogen, the body triggers a powerful contraction of the muscles involved in respiration, which forces air out rapidly. This action can dislodge and expel microbes or debris, reducing the chance of infection.

These mechanisms are particularly important because the respiratory tract is constantly exposed to airborne pathogens. By trapping these harmful agents in mucus produced by the respiratory lining and then expelling them through coughing or sneezing, the body minimizes the risk of infection and maintains respiratory health.

In contrast, the other options provide protective functions in different contexts. Skin acts as a physical barrier against pathogens but is not specific to the respiratory tract. Tears help wash away irritants from the eyes and can flush out bacteria, but they do not play a role in the respiratory system. Hydrochloric acid in the stomach plays a key role in digestion and protection against pathogens that are ingested rather than inhaled. Each of these options represents a form of defense, but coughing and sneezing are specifically tailored to the respiratory system's needs.