What is formed when sebum produced by the oil glands mixes with the body's perspiration?

• A. Medulla
• B. Acid mantle
• C. Arrector pili
• D. Sebaceous glands

Answer: (B)

The main idea is the protective film on the skin formed by mixing oil with sweat. When sebum from oil glands combines with body perspiration, it creates the acid mantle, a thin, slightly acidic layer that coats the skin’s surface. This film helps shield against bacteria and environmental factors while helping to keep the skin moisturized and maintain a slightly acidic pH (roughly around 4.5–5.5). The other terms refer to different structures: the medulla is part of a hair shaft, the arrector pili is the tiny muscle that makes hair stand up, and sebaceous glands are the oil-producing glands themselves, not the film formed by their secretions mixing with sweat.