What is the primary function of lymph nodes within the immune system?

Lymph nodes play a crucial role in the immune system, and their primary function is the activation of lymphocytes. Lymphocytes, which include T cells and B cells, are essential for the adaptive immune response. When pathogens, such as bacteria or viruses, invade the body, they are often filtered through the lymphatic system, where lymph nodes are strategically located.

Inside the lymph nodes, antigens from these pathogens are presented to naive lymphocytes. This presentation is typically facilitated by antigen-presenting cells, such as dendritic cells. Once the lymphocytes recognize the antigens, they become activated, proliferate, and differentiate into effector cells capable of targeting and eliminating the specific pathogens. This activation process is vital for mounting an effective immune response.

The other options do not accurately reflect the primary function of lymph nodes. They do not produce red blood cells, which occurs primarily in the bone marrow. While lymph nodes can "store" pathogens in terms of presenting antigens to lymphocytes, this is not their main function; rather, it’s a part of the activation process. Additionally, lymph nodes do not directly circulate nutrients; that role is mainly taken on by the bloodstream and associated vascular systems. Thus, the activation of lymphocytes stands out