The human circulatory system A) helps maintain a constant body temperature.
B) carries cells that help protect the body from disease.
C) helps the body regulate body temperature.
D) all of the above

The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.

https://kidshealth.org/en/teens/heart.html

Gravitational force i believe