What is the main function of lymph nodes?

Trapping microorganisms or antigens

The correct answer is Option (3) - Trapping microorganisms or antigens

Lymph nodes are part of the lymphatic system, which is a network of vessels and tissues involved in immune responses. The lymph nodes are small solid structures located at different points along the lymphatic system. Lymph nodes serve to trap the micro-organisms or other antigens, which happen to get into the lymph and tissue fluid. Antigens trapped in the lymph nodes are responsible for the activation of lymphocytes present there and cause the immune response.