Which system includes the skin, hair, and nails?

• A. Integumentary system
• B. Nervous system
• C. Skeletal system
• D. Endocrine system

Answer: (A)

The skin, hair, and nails form the body's outer protective covering and regulatory interface, which is the role of the integumentary system. This system includes not only the skin but also its appendages—hair and nails—and associated glands and structures, all working together to protect internal tissues, regulate temperature, sense touch, and aid in vitamin D production. The nervous system is made up of the brain, spinal cord, and nerves; the skeletal system is the framework of bones; the endocrine system consists of glands that release hormones. So, the group that includes skin, hair, and nails is the integumentary system.