Active muscles demand huge amounts of oxygen, and the circulatory system works hard to provide it. Blood carries oxygen to the muscles. When the body is at rest, blood carries nutrients to the muscles so that they can repair and rebuild themselves. Blood also carries away the waste products that hard-working muscles produce, back out through the lungs to be filtered.
so they Circulatory system xx muscular system :)
Explanation:
soil organisms which range in size from microscopic cells that digest decaying organic material to small mammals that live primarily on other soil organisms play an important role in maintaining fertility structure drainage and aeration of soil
