Question

skin, hair and nails are parts of the—
o musculoskeletal system.
o integumentary system.
o nervous system.

Explanation:

The integumentary system consists of the skin, hair, nails, and associated glands. It serves as a protective barrier for the body. The musculoskeletal system is related to bones and muscles, and the nervous system is about nerves and the brain - neither of which include skin, hair, and nails as main components.

Answer:

Integumentary system.