Why do nearly all infections produce similar symptoms, such as fever, sleepiness, and loss of energy?

a. Every infection damages the body’s ability to maintain body temperature and overall activity.

b. “Sickness behaviors” are an effective way for a sick person to gain sympathy and help.

c. Infectious particles clog the arteries, making it difficult for other chemicals to reach their targets.

d. The immune system sends prostaglandins to the brain, where they stimulate the hypothalamus to produce these effects.