Final answer:
Most cloned B cells become plasma cells that mass produce and secrete antibodies specific to a particular antigen, playing a key role in the body's immune response.
Step-by-step explanation:
The correct answer to the question is: 1. B cells; antibodies.
Most cloned B cells become plasma cells, which are specialized cells derived from B cells. These plasma cells act as antibody factories, producing high levels of antibodies specific to a particular antigen they've encountered. Antibodies are crucial proteins used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. When a B cell encounters an antigen, it can be activated and undergo clonal expansion, resulting in the creation of many plasma cells that all produce the same type of antibody specific to that antigen. This focused response allows the immune system to target and eliminate specific pathogens effectively.