What happens to the total blood flow during heavy exercise compared to at rest?

Blood flow is greater when you exercise because the blood vessels in your muscles dilate. Imagine water flowing through a fire hose compared to a garden hose. Adenosine triphosphate, or ATP, is the way your body uses biochemicals to store and use energy. When ATP gets used up in working muscles, the muscles themselves produce metabolic byproducts (for example, adenosine, hydrogen ions and carbon dioxide). As these byproducts leave the muscle cells, they cause small, thin-walled blood vessels (capillaries) within the muscle to expand or dilate, which is called vasodilation. The dilated capillaries allow increased blood flow, which delivers more oxygenated blood to the working muscle.

The right answe is C.

Explanation:

The limit to how large any given population could be is defined by the concept of " carrying capacity". It refers to the fact that in nature populations grow much faster than resources do, and this impose a limit to population sizes (if there is no enough nutrition sources, the number of individual can not go up).