Herd immunity involves ________.


A) encouraging individuals to work and live in close proximity to each other to prevent spread of a disease outside of a population

B) maintaining a 100% vaccination rate among farm workers to prevent the spread of zoonotic diseases

C) keeping bovine diseases to a minimum so they do not spread to the human population

D) maintaining a certain level of immunized individuals in a society to prevent a pathogen from circulating through the population