<span>A.it increases the efficiency with which the body delivers oxygen and nutrients to its cells</span>
I can help you if you provide a little more information :)
Get inside and wait it out
The correct option is this: IT INCREASES THE AMOUNT OF ENERGY YOUR BODY USES AT REST.
Regular exercise increases the amount of energy that one burns while exercising, but it does not stop there, it also increases the amount of energy that one burns while the body is at rest. This is because regular exercise speed up the rate of metabolism of the body and this rate remain high even when the body is at rest, thus, an individual who exercises regularly will lose more energy at rest than some one who is not actively exercising.<span />
