Final answer:
The primary function of the first line of defense in microbiota is to provide a generalized and nonspecific set of defenses against pathogens.
Step-by-step explanation:
The primary function of the first line of defense in microbiota is to provide a generalized and nonspecific set of defenses against a class or group of pathogens. This includes barrier mechanisms such as the secretion of mucus, the secretion of the bactericidal enzyme lysozyme, and phagocytosis. These defenses help to prevent the attachment and colonization of pathogens, and aid in their removal from the body.