Answer:
A. Vena cava
Explanation:
The aorta can't be the answer because it is the largest artery in the human body and it carries oxygenated blood. The pulmonary artery carries deoxygenated blood into the lungs for oxygenation. The pulmonary veins transfer oxygenated blood from the lungs to the heart. And lastly, the vena cava is the right answer and it returns deoxygenated blood back into the heart.
