What is the function of mucus?

Mucus plays a crucial role as a protective secretion of the mucous membranes found in various parts of the body, including the respiratory, gastrointestinal, and urogenital tracts. Its primary function is to trap pathogens, dust, and other foreign particles that enter the body, thereby helping to prevent infection and irritation. Additionally, mucus keeps mucous membranes moist, which is essential for their proper functioning. By providing a barrier, it helps maintain homeostasis and supports the immune response in the areas it lines.

In contrast to the other choices, which misrepresent the role of mucus, the correct answer highlights its protective aspect. Mucus is not a food source for bacteria; instead, while some bacteria may utilize it for nutrients, its primary function is protective. It also does not absorb nutrients directly; that process is primarily managed by enzymes and specialized cells in the digestive tract. Lastly, mucus is not a waste product; rather, it is a vital secretion that supports health and well-being by safeguarding internal structures.