Which of the following describes sebum?

Sebum is best described as a secretion of the sebaceous glands. The sebaceous glands are located in the skin and are responsible for producing sebum, an oily substance that serves several crucial functions. Sebum helps to keep the skin moisturized, provides a protective barrier against bacteria and other pathogens, and contributes to maintaining overall skin health by preventing dryness.

Understanding sebum and its production is essential in fields like dermatology and forensic science, especially regarding how skin characteristics and residues may be relevant for latent print analysis and other investigations. The other options do not accurately define sebum; they involve different biological substances or processes that are not related to its origin or function.