Which of the following correctly lists the three main types of blood vessels?

• A. Capillaries, arteries and veins
• B. Lymphatics
• C. Nerves and capillaries
• D. Muscles and veins

Answer: (A)

Capillaries, arteries and veins are the three main blood vessels. Arteries carry blood away from the heart, supplying tissues with oxygen and nutrients. Veins return blood to the heart, typically carrying deoxygenated blood back to the heart (with some exceptions in the lungs). Capillaries are the tiny exchanges between blood and tissues, where oxygen, carbon dioxide and other substances pass in and out.

Lymphatics are part of the lymphatic system, not the blood vessel network, while nerves are not vessels at all, and muscles are tissue, not vessels. So the grouping that correctly lists the three main blood vessel types is capillaries, arteries and veins.