Which statement best describes the integumentary system's role in immunity?

• A. It provides innate immunity
• B. It stores hormones
• C. It helps regulate digestion
• D. It produces antibodies

Answer: (A)

The skin serves as the body's first line of defense, providing innate immunity by forming a physical barrier that blocks pathogens from entering. The integumentary system also uses chemical defenses—sweat and oils create an acidic, inhospitable environment, and antimicrobial peptides further limit microbes. Immune cells in the skin, like Langerhans cells, help detect invaders and coordinate the response. Because of these barrier and innate-defense features, it best describes the integumentary system’s role in immunity. The other choices point to functions of other systems or to adaptive immunity (antibody production by B cells), which are not roles of the skin.