What is the primary function of keratinocytes?

Keratinocytes are the predominant cell type found in the epidermis, the outermost layer of the skin. Their primary function is to produce keratin, a tough, fibrous protein that plays a critical role in creating a protective barrier for the skin. This protein is essential for the skin's resilience and helps prevent water loss, protecting the body from environmental damage, pathogens, and chemical exposures.

While the other options mention important functions related to skin health and the immune system, they do not specifically pertain to the primary role of keratinocytes. For instance, the production of pigment that absorbs UV rays is mainly the function of melanocytes, another cell type in the skin. Collagen production is primarily associated with fibroblasts in the dermal layer, not keratinocytes. Immune responses are facilitated by Langerhans cells, which are also found in the epidermis but are distinct from keratinocytes. Therefore, the correct answer focuses on the key protective role of keratinocytes in skin health.