In terms of immune response, what does a B lymphocyte primarily do?

B lymphocytes, or B cells, play a crucial role in the adaptive immune response primarily through the production of antibodies. Once activated by encountering an antigen or through help from T-helper cells, B cells differentiate into plasma cells, which are responsible for generating specific antibodies. These antibodies bind to antigens present on pathogens, such as bacteria and viruses, effectively neutralizing them and marking them for destruction by other immune cells.

This ability to produce antibodies is key to the immune response, providing long-term immunity and memory against previously encountered pathogens. Therefore, the correct answer highlights this fundamental function of B lymphocytes in protecting the body against infections through the creation of a robust humoral response.