Answer:
A.
Explanation:
First off, the system contains hair, skin, hair, nails and exocrine glands (sweat, saliva, ect). It is not c, since u are not looking for that. It is may be d, because the immune system does that. It is not e, because again, skin. It is probably not b either, since your brain is the one that keeps your body temperature constant. The answer is a.
