The correct option is B T-lymphocyte
Cellular immunity is a kind of immunity that does not involve antibodies but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. B-lymphocytes are involved in humoral immunity. Erythrocytes or RBCs and thrombocytes or platelets don't play a role in immunity. Thus, the correct answer is option A.