The correct option is B
Monoclonal antibodies are used to identify and target the cancer cells
Cancer is a dreadful disease. It is an abnormal and uncontrolled division of cells, that invade and destroy the surrounding tissues.
The common approaches for the treatment of cancer are surgery, radiation therapy, chemotherapy and immunotherapy.
Even antibodies are used for the treatment of cancer. Specific antibodies (monoclonal antibodies) are used for detection of certain cancers. Antibodies are proteins (immunoglobulins) that fight against the foreign agents or infected cells. So option b is correct.
The clonal selection theory states that a single plasma B cell clone will produce one specific antibody population. These antibodies are called monoclonal antibodies. Thus, monoclonal antibodies (mAbs) made from clones of a unique B cell, will bind to antigens on the surface of cancer cells rather than healthy cells and lead to their destruction. So option a is wrong as the diversified set of antibodies are not used to fight against cancer.
Monoclonal antibodies are artificially made molecules that serve as substitutes for antibodies to restore, enhance or mimic the immune system's attack on cancer cells.
Monoclonal antibodies attach themselves to a specific molecule on the surface of a cell, called an antigen. When an antibody binds to the antigen, it serves as an identification mark to attract immune cells like T cells, macrophages (to engulf cancer cells) to trigger cell destruction. Hence option c is wrong as the antibodies cannot directly engulf cancer cells.
mAbs bring T cells or macrophages close to them to identify and kill the cancer cells. For example, killing of leukemia cells. Option d is wrong as the antibodies bring the T cells or macrophages close to them not the cancerous cells.
Figure : Mechanism of action of monoclonal antibody