Answer: C. help control body temperature.
The cardiovascular system consists of the heart, together with a closed system of vessels which includes the veins, arteries, and capillaries. The capillaries are the most numerous of the blood vessels and they help in forming a connection between the veins and the arteries. Capillaries can also be used for thermoregulation where they can help in regulating body temperature. Through vasoconstriction and vasodilation, capillaries can limit blood speed. Through shunting, blood flow to an area can be restricted during cold weather and through flushing, the blood flow is increased during hotter periods. With this, the body temperature is regulated.