Carry deoxygenated blood back toward the heart.

• A. Arteries
• B. Capillaries
• C. Venules
• D. Veins

Answer: (D)

Veins are the vessels that carry blood back toward the heart. In the body’s circulation, blood delivers oxygen to tissues and collects carbon dioxide, becoming deoxygenated. Veins gather this low-oxygen blood from the body and return it to the heart to be pumped to the lungs for re-oxygenation. This return-to-the-heart role distinguishes veins from arteries, which move blood away from the heart (usually oxygenated), and from capillaries, where gas exchange occurs, with venules serving as small pathways that feed into veins. Remember the exception in the lungs: pulmonary veins carry oxygenated blood from the lungs to the heart, while pulmonary arteries carry deoxygenated blood to the lungs.