Which of the following contains oxygenated blood?

• A. Pulmonary arteries
• B. Pulmonary veins
• C. Superior vena cava
• D. Aorta

Answer: (B)

Oxygenated blood is the blood that has picked up oxygen in the lungs and is headed back to the heart to be pumped to the rest of the body. The vessels that return this oxygen-rich blood from the lungs to the heart are the pulmonary veins. They bring blood into the left atrium after it has been oxygenated, which is why they’re considered to carry oxygenated blood.

In contrast, the pulmonary arteries carry blood away from the heart to the lungs and this blood is low in oxygen at that stage. The superior vena cava brings deoxygenated blood from the upper body into the right atrium. The aorta, on the other hand, carries oxygenated blood from the left ventricle to the systemic circulation, delivering it to tissues throughout the body. So while the aorta does contain oxygenated blood, the vessel that specifically returns oxygenated blood from the lungs to the heart is the pulmonary vein, which is why it’s the best choice for this question.