Which of the following best explains why the secondary immune system response is
both stronger and faster than the primary immune response?
A) High concentrations of antibodies are already present.
B) Memory cells produced during the first exposure to the antigen can rapidly
respond to a second exposure.
C) Plasma cells remain activated after they are exposed to the antigen in the
primary response.
D) The exposure to an antigen is always stronger the second time it is
encountered.
