What is the main function of B-lymphocytes?

The main function of B-lymphocytes, also known as B cells, is to produce antibodies that help to fight infections. When B cells encounter pathogens such as bacteria or viruses, they can differentiate into plasma cells, which are specialized for the production of antibodies. These antibodies are proteins that specifically recognize and bind to antigens on the surface of pathogens, marking them for destruction by other components of the immune system. This process is crucial for the adaptive immune response, as it helps to establish immunity against previously encountered infections.

The role of B-lymphocytes in antibody production is vital for protecting the body against various infectious agents, making them a key component of the immune system. In contrast, other options pertain to different bodily functions: insulin production is associated with pancreatic function, blood clotting involves platelets and other clotting factors, and oxygen transport is primarily the role of red blood cells. Thus, the answer highlighting B-lymphocytes' production of antibodies is the correct representation of their main function in the immune response.