Smokers Tend to Cough Frequently Because Coughing

Smokers tend to cough frequently because coughing

A) releases the tar that fills numerous alveoli.
B) is a response to histamine that is released when smoke narrows the airway.
C) clears the mucus, which the paralyzed cilia can no longer do.
D) assists in release of surfactant, which is inhibited by smoking.
E) assists the diaphragm in contracting, improving exhalation.