Which of the Following Factors Contribute to a Reduction in an Elderly

Which of the following factors contribute to a reduction in an elderly person's mucociliary clearance?
1) Increase in ciliary activity
2) Degenerative changes in the epithelial cells of the mucous membrane
3) Decrease in the phagocytic activity of macrophages in the mucous membrane
4) Decrease in the cough reflex

A) 1 and 3
B) 2 and 4
C) 1, 2, and 3
D) 2, 3, and 4