Question

What does the respiratory system do?

a. moves blood around the body
b. defends against invaders
c. sends hormones to the body
d. brings oxygen into the body?

Answer 1

The respiratory system is the organ system that involves breathing. Humans breathe in oxygen. Another way to find the answer is to break down the word respiration. Respiration means "to breathe" or "the action of breathing". The answer is D.