Which organ system forms the external covering and protects tissues?

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

Answer: (D)

The organ system that forms the external covering and protects tissues is the one that includes the skin, hair, nails, and associated glands. This integumentary system acts as the body’s first line of defense, shielding underlying tissues from injury, pathogens, and dehydration, while also helping regulate body temperature and providing sensory information. The other systems don’t serve as the external barrier: the skeletal system offers internal support and protection for some organs and forms the framework for movement; the muscular system enables movement and generates heat; the endocrine system releases hormones that regulate processes throughout the body. Because forming the external protective covering is a defining role of the integumentary system, it is the best answer.