What is the main function of sebaceous glands?

Sebaceous glands play a crucial role in the health and maintenance of the skin and hair by producing oil, known as sebum. This oil serves several important functions, primarily acting as a natural moisturizer that keeps the skin and hair hydrated. By lubricating these areas, sebum helps to prevent dryness and protects against environmental damage. Additionally, sebum has antimicrobial properties, which can help in reducing the risk of infections on the skin.

Other options relate to different physiological processes: sweat production is handled by sweat glands, nutrient absorption is a function of the digestive system not associated with skin structures, and temperature regulation primarily involves sweat glands and blood flow adjustments, rather than the action of sebaceous glands. Thus, the primary and defining role of sebaceous glands is indeed to produce oil that keeps the skin and hair properly conditioned.