Which of the following does NOT deliver oxygen-poor blood to the heart?

• A. Pulmonary vein
• B. Inferior vena cava
• C. Coronary sinus
• D. Superior vena cava

Answer: (A)

Verified step by step guidance

1. Understand the role of each blood vessel mentioned in the problem. The pulmonary vein, inferior vena cava, coronary sinus, and superior vena cava are all involved in transporting blood to or from the heart.
2. Recall that oxygen-poor blood is blood that has already circulated through the body and is returning to the heart to be sent to the lungs for oxygenation. Oxygen-rich blood is blood that has been oxygenated in the lungs and is being delivered to the body.
3. Identify the function of the pulmonary vein. The pulmonary vein is unique because it carries oxygen-rich blood from the lungs to the left atrium of the heart, unlike the other vessels listed, which carry oxygen-poor blood.
4. Examine the functions of the inferior vena cava, coronary sinus, and superior vena cava. These vessels all deliver oxygen-poor blood to the right atrium of the heart. The inferior vena cava carries blood from the lower body, the superior vena cava carries blood from the upper body, and the coronary sinus carries blood from the heart's own circulation.
5. Conclude that the pulmonary vein does NOT deliver oxygen-poor blood to the heart, as it carries oxygen-rich blood instead. This distinguishes it from the other vessels listed.