Question

How does regular exercise help maintain a healthy respiratory system?

A. It helps cilia in the lungs eliminate mucus.
B. It helps lungs from becoming too large.
C. it helps lungs exchange gases at a slower rate.
D. It helps lungs become more efficient at gas exchange.

Answer 1

It helps lungs become more efficient at gas exchange

Answer 2

D

Explanation:

It helps lungs become more efficient at gas exchange.