Which of the following is a primary function of the skin?

Primary functions of the skin include protection (acting as a barrier against the environment, microbes, and water loss), sensation (detecting touch, pressure, heat, cold, and pain through nerve endings), and heat regulation (controlling body temperature via blood flow and sweating), along with secretion of sebum, limited excretion, and limited absorption. The skin does not produce blood cells, digest food, or pump blood. Understanding the skin's core functions underpins safe and effective skincare services and is foundational exam content.