What is the primary purpose of sebum in the skin?

Sebum plays a vital role in maintaining the skin's health by acting as a natural moisturizer. Its primary purpose is to retain moisture in the skin, which prevents dryness and helps maintain the skin's elasticity and suppleness. This oily substance is produced by sebaceous glands and creates a barrier that not only locks in moisture but also gives the skin its smooth and hydrated appearance.

While sebum does provide some protective functions and contributes to the health of hair by keeping it lubricated, its most crucial role is in moisture retention. The other options, such as providing nutrients or enhancing skin color, do not accurately capture the primary function of sebum in the context of skincare.