Answer: b. integumentary system.
Explanation:
Integumentary system includes the skin and other protective appendages of the body which provides protection against the loss of water, injury and other damages could be caused by the external environment. The integumentary system involves hair, feathers, nails, scales and hooves. It also functions in eliminating the waste products, protecting the body from diseases and regulating the body temperatures.
On the basis of the above explanation, Skin, nails and hair make up the integumentary system is the correct option.
