Which of the following is a role of lymph nodes?
they return lymph to circulation.
they produce lymph.
they filter lymph.
they produce red blood cells.

They filter lymph.

Explanation: Lymph nodes filter lymph, a fluid that comes from the blood plasma and passes through the lymph nodes; small structures that consist of immune cells. Their function is to engulf foreign parcticles. They prevent these foreign matters from circulating in the blood stream, playing a very important role in the immune system.