Question

multiple choice question
what is the smallest - diameter blood vessel?
o a capillary
o an arteriole
o an artery
o a vein
o a venule

Explanation:

Capillaries are the smallest - diameter blood vessels. They connect arterioles and venules and have a very thin wall which allows for the exchange of substances between blood and tissues. Arterioles are smaller arteries that branch off from arteries, arteries carry blood away from the heart, veins carry blood back to the heart, and venules are smaller veins that drain blood from capillaries into larger veins.

Answer:

A. A capillary