Final answer:
The majority of lymphocytes observed in the peripheral blood are T cells and B cells. These cells are essential for the immune response and play a role in recognizing and responding to particular pathogens.
Step-by-step explanation:
The majority of lymphocytes observed in the peripheral blood are T cells and B cells. T cells are involved in the cell-mediated immune response, while B cells are part of the humoral immune response. Both T cells and B cells are vital for the immune response and play a role in recognizing and responding to particular pathogens.