13. What are the functions of the atria of the heart?
a. They are the pumping chambers, moving the blood to the lungs and to the body.
b. They are the receiving chambers of the heart, accepting blood from the body and
from the lungs
C. They force the blood out into the arteries
d. They control movement of the blood into the heart chambers and out of the aorta
and the pulmonary artery.​