The correct option is A Use of immunosuppressants
Autoimmune diseases are caused when the immune system of the body fails to distinguish between its own antigens and foreign antigens and starts attacking the self cells. One of the examples of autoimmune diseases is rheumatoid arthritis.
Immunosuppressant drugs are used for the treatment of autoimmune diseases. Immunosuppressants suppress the activity of the immune system and reduce the severity of the autoimmune disorders.
Autoimmune diseases are not caused due to the invasion of viruses or any other pathogenic microbes. So, antibiotics (against bacteria) and antiviral (against virus) drugs won’t be of much use in treating autoimmune diseases.
Allergens are foreign substances capable of arousing an allergic response in a susceptible person. However they do not cause the immune cells to attack the self cells. Hence, avoding allergens is not effective against autoimmune diseases.