During the natural process of aging, the number of functional cilia in the respiratory system decreases, resulting in: select one: a. a decreased ability to cough. b. baseline respiratory distress. c. air-trapping within the alveoli. d. an increased risk of copd.

A. Decreased ability to cough

Explanation:

In our respiratory tract, we have hairs that are known as cilia. Cilia act as sweepers that "beat" (the action of moving) mucous up the respiratory tract and into the mouth so that the lungs remain mucous free. The action of coughing is triggered by mucous approaching the top of the airway and the body needs to expel the mucous.

When the cilia are few in numbers, there is not as strong an action compared to if there were many, hence it is less likely the person will cough.