An Individual with Cystic Fibrosis Has Thick Mucus Lining the Lungs

An individual with cystic fibrosis has thick mucus lining the lungs, and will commonly suffer from bacterial infections in the lungs. In an individual without cystic fibrosis, the mucus in the lungs and respiratory tract are important for the removal of inhaled pathogens like bacteria. Why isn't this also the case for someone with cystic fibrosis?

A) In individuals without cystic fibrosis, the pathogens trapped in mucus are moved out of the body by cilia. In cystic fibrosis patients, the mucus is too thick to be moved by the cilia.
B) In individuals without cystic fibrosis, pathogens are trapped in the mucus and divide there instead of invading cells in the respiratory tract. In cystic fibrosis patients, the pathogen moves from the mucus to the lungs undetected.
C) The immune system in cystic fibrosis patients is suppressed unlike that of individuals without cystic fibrosis.
D) Individuals without cystic fibrosis don't have to inhale as deeply as cystic fibrosis patients, so pathogens are less likely to enter the respiratory tract.