Read the following Assertion and Reason and choose the correct option. Assertion: Modern-day lifestyle and environmental factors have led to an increase in allergies and asthma in children. Reason: The increased sensitivity to allergens may be due to the protected environments and lower exposure to environmental antigens early in life.

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