In an investigation of the immune response, a volunteer was exposed to two different antigens, X and Y. The concentration of antibodies in the blood, relative to each other, was recorded at regular intervals throughout 60 days. The graph indicates the time at which the volunteer was exposed to each antigen and plots antibody concentration against time for antigens X and Y. What explains the results shown on the graph?
- AA primary and secondary immune response against antigen X occurred, with the memory B-lymphocytes inhibiting the secondary immune response against antigen Y.
- BA primary immune response to antigen Y occurred and memory B-lymphocytes specific to antigen Y enhanced the secondary immune response to antigen X.
- CMemory B-lymphocytes specific to antigen X enabled a secondary immune response to occur; different B-lymphocytes were activated for a primary immune response for antigen Y.
- DPlasma cells remaining from the first exposure to antigen X undergo rapid clonal selection to produce high levels of antibody against antigen X and lower levels of antibody against antigen Y.