Why Do Cigarette Smokers Cough More Than Nonsmokers

Why do cigarette smokers cough more than nonsmokers?

A) Cigarette smoking partially paralyzes the muscles in the lungs,resulting in an increased residual volume,and coughing exchanges this "dead air."
B) Cigarette smoke harms the cilia that normally move debris out of the lungs,and coughing is the remaining way to clean the lungs.
C) The tar in cigarette smoke tends to make alveoli stick together,and coughing separates them.
D) By raising the pressure in the lungs,coughing forces more oxygen into the blood.