An agent that promotes the discharge of mucus from the respiratory tract is known as what?

The correct term for an agent that promotes the discharge of mucus from the respiratory tract is an expectorant. Expectorants work by increasing the hydration and volume of respiratory secretions, which helps to loosen mucus and make it easier to cough up. This action can help clear the airways and alleviate congestion, making it particularly useful in conditions like bronchitis or pneumonia where mucus accumulates.

Antitussives, on the other hand, are designed to suppress coughing rather than promote the expulsion of mucus. Decongestants focus on reducing swelling in the nasal passages to relieve nasal congestion but do not specifically assist in expelling mucus from the respiratory system. Bronchodilators are medications that relax muscle tissues in the airways, making it easier to breathe, but they also do not directly promote mucus clearance.

Thus, expectorants specifically target mucus release while the other options address different aspects of respiratory issues. This is why the choice of expectorant is the most accurate in this context.