Which of the choices below explains why the arterioles are known as resistance vessels?

There are choices for this question namely:

A) Their prime function is the exchange of nutrients and wastes between the blood and tissue cells.
B) The contraction and relaxation of the smooth muscle in their walls can change their diameter. 
C) They distribute blood to various parts of the body.
D) They contain a large quantity of elastic tissue.

The correct answer is "the contraction and relaxation of smooth muscle in their walls can change their diameter". In the systemic circulation, the arterioles contribute most of the total peripheral resistance due to the abundance of smooth muscles in their vessel walls; allowing them to contract and decrease the lumen of the arterioles thereby increasing peripheral vascular resistance.