What is the primary role of sebaceous glands?

Sebaceous glands primarily function to produce oil, also known as sebum. Sebum is an oily substance that plays a critical role in maintaining the health and hydration of the skin and hair. It helps to form a protective barrier on the skin's surface, which prevents water loss and provides some antimicrobial properties. This oil is essential for keeping the skin moisturized and preventing dryness, as well as contributing to the overall appearance and texture of the skin.

The other options relate to different bodily functions or glands. For instance, sweat production is the responsibility of sweat glands, not sebaceous glands. The filtering of lymph is done by lymph nodes, while the transportation of oxygen is primarily managed by red blood cells in the circulatory system. Understanding the specific roles of different glands in the body emphasizes the diverse physiological processes that contribute to overall health.