Final answer:
The mature versions of B cells that act as antibody factories in the body are known as plasma cells, which produce and secrete large quantities of antibodies, a critical component of the immune system's defense strategy.
Step-by-step explanation:
The antibody factories in the body are the mature versions of B lymphocytes or B cells. Once a B cell is activated, it undergoes clonal expansion, and the daughter cells differentiate into plasma cells. These plasma cells are essentially antibody factories as they are responsible for producing and secreting large quantities of antibodies, which are crucial components of the body's humoral immune response. Antibodies, or immunoglobulins, are glycoproteins that bind to specific antigens, signaling for the destruction of these antigens by the immune system.