Question

eventually, that branching results in microscopic arteries called arterioles. the arterioles play a key role in regulating blood flow into the tissue capillaries. about 10 percent of the total blood volume is in the systemic arterial system at any given time. which word or phrase from the selection helps you understand the size of arterioles? a microscopic b arteries c 10 percent d volume

Explanation:

The word "microscopic" means extremely small, visible only under a microscope. It directly gives an indication of the small - size nature of arterioles. "Arteries" is a general term and doesn't convey size. "10 percent" refers to blood volume proportion, not size. "Volume" is a general measurement term and not related to the size of arterioles.

Answer:

A. microscopic