A 90-Year-Old Patient Complains to the Nurse of Shortness of Breath

A 90-year-old patient complains to the nurse of shortness of breath after walking up a flight of stairs.The nurse explains that this problem is a result of age-related changes,such as a(n) :

A) Flexible rib cage
B) High-arched diaphragm
C) Increased chest movement
D) Enlarged bronchioles