Which statement about B lymphocytes is correct?

• A. Phagocytic
• B. Participate in antibody-dependent cellular cytotoxicity
• C. Contain surface immunoglobulins
• D. Secrete the C5 component

Answer: (C)

B lymphocytes are defined by having surface immunoglobulins that act as their antigen receptors. These membrane-bound antibodies recognize specific antigens, triggering activation, clonal expansion, and differentiation into plasma cells that secrete antibodies. They also present antigen to helper T cells via MHC II, supporting the adaptive response. Phagocytosis is a function of macrophages and neutrophils, not B cells. Antibody‑dependent cellular cytotoxicity is mainly carried out by natural killer cells and other Fc receptor–bearing effector cells, not by B cells themselves. The C5 component of the complement system is produced by the liver and other tissues, not by B lymphocytes. Thus, containing surface immunoglobulins is the best description of a key characteristic of B cells.