Read the passage about an athlete.

when an athlete's body temperature begins to climb, blood vessels in the skin dilate. as a result, the athlete's face turns red because warm, oxygenated blood moves to the surface of the skin. this process to reduce overall body temperature and prevent overheating.
which organ system most likely to keep an athlete from overheating?

a
the digestive system

b
the circulatory system

c
the respiratory system

d
the reproductive system