The three types of lymphocytes are __________, __________, and __________.
◦ natural killer cells (NK cells), B lymphocytes (B cells), and T lymphocytes (T cells)
◦ P lymphocytes (P cells), D lymphocytes (D cells), and Q lymphocytes (Q cells)
◦ virucytes (V cells), bacterocytes (B cells), and trancytes (T cells)
◦ antigens, pathogens, and harmogens