B. Sounds like the best awnser to me.
A quick search provides me with this: In the kidneys, the cardiovascular system maintains homeostasis by providing adequate blood pressure that the kidneys utilize to filter toxins and waste from the blood and subsequently the body. The cardiovascular system also helps the skin in homeostasis by regulating body temperature. / Capillary action (sometimes capillarity, capillary motion, capillary effect, or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a cell. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion within the liquid) and adhesive forces between the liquid and container wall act to propel the liquid.
From this I would say your awnser is B.
C Thermoregulation and hormone transport
The Circulatory System delivers oxygen and nutrients in the blood to the surrounding cells to maintain Homeostasis. The blood in the Circulatory System is needed throughout the body so that other systems work properly. Like for instance the Nervous System has the brain, and the brain needs blood to function.
