Acquired immune response.
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A. A   helper  T  cell  stimulates  the  humoral  (antibody-mediated)
response  by  activating  B cells, which can secrete antibodies to
defend against extracellular pathogens.
B. A  helper  T cell can also stimulate the cell-mediated response by
activating  cytotoxic T cells, which bind to and lyse target cells
containing intracellular pathogens.