Which of the following describes sebum?

Sebum is an oily substance produced by sebaceous glands in the skin. Its primary function is to lubricate and waterproof the skin and hair, helping to prevent dryness and providing a protective barrier against environmental factors. The composition of sebum includes triglycerides, wax esters, squalene, and free fatty acids, all of which contribute to its oily nature.

While proteins, water, and carbohydrates are important components of the body's composition, they do not describe sebum accurately. Sebum's unique oily quality is crucial for maintaining healthy skin and hair, making it an essential part of the skin's barrier function.