Which option denotes a primary function of wei qi?

Wei qi, often referred to as "defensive qi," plays a crucial role in the body's immune response and overall health maintenance. Its primary function is to protect the body against external pathogens, such as viruses and bacteria. Wei qi circulates just beneath the skin and is responsible for creating a protective barrier that helps prevent illness and keeps the body safe from external threats.

While regulating body temperature, enhancing digestion, and promoting qi circulation are important aspects of overall health and may involve other types of qi or bodily functions, they are not the primary role of wei qi. The emphasis on protection against pathogens clearly defines the role of wei qi as essential for maintaining the integrity of the body's defenses.