13. Which tells that the organs of Circulatory System work together?

A. Skin has three main functions: protection, regulation and sensation.

B. When you exhale, the diaphragm relaxes and the air is pushed out of lungs.

C. Epidermis is to acts as a physical and biological barrier to the external environment.

D. Heart pumps the blood with food nutrients and distribute it to the body through the blood vessels.​