How do the circulatory and respiratory systems play a role in track and field?

Track and field requires a lot of running

Explanation:

When someone runs, blood needs to be circulated throughout the whole body.  Constant blood is pushed throughout the body due to blood vessels in our circulatory system.  The heart pumps faster so more blood is produced. Oxygen is needs to be reached to muscles.  When someone runs, they tend to breathe heavier.  Heavy breathing and more breathing is done by the respiratory system.  Lungs need to filter air and therefore the respiratory system works hard as well

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.