Which are the physical (P) chemical (C) and biological (B) immune responses?

Physical immune responses (P) include barriers like skin and mucous membranes that prevent pathogen entry. Chemical responses (C) involve substances such as antimicrobial peptides and the action of enzymes in saliva and tears that neutralize pathogens. Biological immune responses (B) consist of the activation of immune cells, such as lymphocytes and macrophages, which target and eliminate infectious agents through adaptive and innate mechanisms. Together, these responses create a comprehensive defense system against infections.