Correct answer: A). Integumentary
The integumentary system composed of the hair, nails, skin, glands, and nerves. Its main function is to provide protection to the body against disease-causing infections such as bacteria and viruses and act as a barrier to harmful ultraviolet radiations, which are coming from the Sun.
It works in coordination with all the other system of the body in order to maintain internal body temperature which is essential for normal body functions. It also helps the body to eliminate waste products.
Hence the correct answer would be option A.