Where do lymph nodes occur in groups throughout the body?

Lymph nodes are strategically located throughout the body, serving as crucial components of the immune system. They are particularly concentrated in specific regions, including the neck, axilla (armpit), abdomen, and groin. These clustered formations enhance the body's ability to filter lymph fluid and capture pathogens, mobilizing immune responses more effectively.

In context, the option indicating that lymph nodes are found in the central nervous system (CNS) is incorrect. The CNS is primarily protected by the blood-brain barrier and does not have lymph nodes, as the immune activity in this region is largely carried out by specialized cells like microglia and the meninges.

By contrast, the other body parts like the lungs and kidneys do not contain lymph nodes in groups as part of their anatomy; instead, lymph nodes are distributed throughout various regions to facilitate immune surveillance and response more effectively.