Edward Jenner Promoted the Use of Cowpox Infection That Was

Edward Jenner promoted the use of cowpox infection that was very similar to the more dangerous smallpox, as a vaccination to provide patients immunity from future smallpox epidemics. This is an example of

A) passive immunity.
B) active immunity.
C) an inflammatory response that decreased the IgE production and increased T cells.
D) developing high levels of complement.
E) developing high levels of interferon although Jenner did not realize these diseases were viral.