Skin, hair, and nails are associated with which body system?

The integumentary system is the correct association for skin, hair, and nails. This system serves as the body's first line of defense against environmental hazards, including pathogens, UV radiation, and physical injuries. The skin, which is the largest organ of this system, plays a crucial role in protecting underlying tissues, regulating body temperature, and providing sensory information.

Hair and nails are also integral components; they offer additional protection and play roles in sensory functions. Hair can help with temperature regulation and protects against UV exposure, while nails protect the tips of fingers and toes, aiding in fine motor tasks. The integumentary system thus encompasses these elements and their functions, making it distinct from other body systems such as the muscular, endocrine, or skeletal systems, which focus on different bodily functions and structures.