Briefly describe what heat stroke does to the body and a situation where it's more likely to affect someone performing a physical activity. (site 1)

Heatstroke is a condition produced by your body heating, usually as a result of lengthened susceptibility to or physical exertion in high temperatures. This most serious form of heat injury, heat stroke, can transpire if your body temperature rises to 104 F (40 C) or higher, the body becomes very hot.

Eventually, that starts to influence the brain, and that's when people begin to get messy and can dissipate consciousness. Other common symptoms involve nausea, seizures, agitation, disorientation, and seldom loss of consciousness or coma.

answer(b) keep oxygenated and deoxygenated blood separate;