Which one among the following cells produces antibodies against a foreign antigen ?

Lymphocytes are a specialized type of white blood cell (leukocyte) that form a critical part of the vertebrate immune system. They are responsible for the body's specific immune response to foreign antigens.

• B-lymphocytes (B cells): These cells are specifically responsible for producing antibodies (immunoglobulins). When a B cell encounters a matching antigen, it matures into a plasma cell that secretes antibodies to neutralize the pathogen.
• T-lymphocytes (T cells): These cells manage cell-mediated immunity, either by destroying infected host cells or by regulating the immune response.

Other options are incorrect because Erythrocytes (red blood cells) transport oxygen and carbon dioxide; Eosinophils are leukocytes involved in fighting multicellular parasites and certain infections; and Platelets (thrombocytes) are cell fragments essential for blood clotting (hemostasis).