Read the following Assertion and Reason and choose the correct option. Assertion: The bone marrow and thymus are primary lymphoid organs where lymphocytes mature and proliferate. Reason: Secondary lymphoid organs are responsible for the final maturation of lymphocytes and include the spleen and lymph nodes.

Step-by-step solution

The human immune system consists of lymphoid organs, tissues, cells and soluble molecules like antibodies. As you have read, immune system is unique in the sense that it recognises foreign antigens, responds to these and remembers them. The immune system also plays an important role in allergic reactions, auto-immune diseases and organ transplantation. Lymphoid organs: These are the organs where origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus w