Final answer:
Erythrocytes are not considered part of the body's nonspecific lines of defense against disease; they are involved in delivering oxygen and do not participate in the immune response. Other options listed like mucous membranes, phagocytic cells, intact skin, and bloodborne chemicals are part of the innate immune system's barriers and responses to pathogens.
Step-by-step explanation:
The part of the body's nonspecific lines of defense against disease not listed in the options is erythrocytes, or red blood cells. These cells are primarily responsible for carrying oxygen to the body's tissues and do not play a direct role in the immune response. The body's first line of defense includes various types of barriers: mechanical, chemical, and biological barriers.
Mechanical barriers, like intact skin and mucous membranes, physically block pathogens from entering the body. Chemical barriers, such as enzymes in sweat and saliva, kill pathogens on body surfaces. Biological barriers include harmless bacteria that outcompete pathogens for nutrients and space.
Additionally, the innate immune system responds with inflammation and other responses if pathogens breach these barriers. Pathogen-Associated Molecular Patterns (PAMPs) would be found on the surface of pathogens, and cells such as phagocytic cells and structures like bloodborne chemicals are involved in the body's immune response to pathogens that make it past the initial barriers.