What are the primary functions of the respiratory system?

The main function of the respiratory system is the exchange of oxygen from the atmosphere for carbon dioxide produced by the cells of the body. Other functions of the respiratory system include participation in the acid-base balance of the body, phonation, pulmonary defense, and metabolism.

Explanation:

answer:

i believe the answer is d).

explanation:

i think this is because you are tearing apart the muscle, and then when you eat, the muscle re-heals, making itself even stronger.

edit: i put b) before but i meant to put d). sorry for the incorrect answer.