Which of the following is the best definition of "microbial antagonism"?
◦ the presence of resident bacteria on the surface of the body and in cavities that connect to the surface
◦ the presence of pathogens on the surface of the skin, which will invade the body through abrasions
◦ the presence of normal microbiota that can become pathogens under certain conditions
◦ the ability of microbiota to mutate into pathogens
◦ the presence of normal microbiota that protect the body by competing with pathogens in a variety of ways to prevent pathogens from invading the body