What do sebaceous glands primarily produce?

Sebaceous glands primarily produce an oily substance known as sebum, which plays a crucial role in moisturizing and protecting the skin and hair. Sebum helps to maintain skin hydration and creates a barrier against bacteria and other pathogens, contributing to overall skin health. By preventing excessive dryness, sebum ensures that the skin remains supple and resilient, which is why the correct answer identifies the primary function of sebaceous glands as producing secretions that moisturize the skin.

Other options provided reflect functions that are not associated with sebaceous glands. For example, the cooling of the body typically involves sweat glands, which are responsible for secreting sweat to help regulate temperature. Sensory perception is managed through different systems in the skin that detect stimuli, while healing processes are supported by various components of the immune system and cell regeneration, rather than by the secretions of sebaceous glands.