I’m not exactly sure, but I’m thinking it may be A . I just learned about this unit previously .
The possibility to answer is C.
Exercise is the primary advice the coaches give to the athletes if they get a cold or any other infection. The main reason behind this advice is the fact that exercising strengthens the immunity of a person. When a person has an infection, the strengthening of the immune system will help his body to efficiently fight against the infectious pathogens. The blood circulation is increased which is involved in the enhancement of the acute immunity of the person.
Parasympathetic nerves govern involuntary actions such as pupil dilation, peristalsis, gland secretions, etc.