Final answer:
Immunoglobulin acts as a stimulating agent in immunotherapy, particularly monoclonal antibody therapy, to induce apoptosis in cancer cells by targeting specific antigens and invoking an immune response. The correct option is a.
Step-by-step explanation:
Immunoglobulin is an example of a stimulating agent used to trigger apoptosis in cancer cells. Monoclonal antibodies, such as immunoglobulins, can be used in cancer immunotherapy and are prepared from cloned immune cells, particularly B-lymphocytes (B-cells). These B-cells secrete immunoglobulins like IgGs, which are targeted to bind to specific cancer cell surface proteins (antigens), and can induce cell death through apoptosis.
Immunoglobulin's function in cancer treatment is multifaceted; it includes blocking the antigen from binding its target, tagging the cancer cells for destruction by different components of the immune system such as macrophages or neutrophils, or by activating the complement cascade. Additionally, immunoglobulin can mediate antibody-dependent cellular cytotoxicity (ADCC) with cells like cytotoxic T cells and natural killer cells, which also contribute to the destruction of cancer cells.