Answer: Lymph node
Explanation:
The lymphatic system of the body works by filtering the blood and remove the harmful pathogen that is present in it.
There are several organs in the lymphatic system that works together at different sites in the body and helps body prevent and cure from infection.
Lymph nodes function to remove pathogen and debris from lymph and it is also referred as filters of lymph. The macrophages and dentritic cells kill the harmful pathogen in the blood.
Hence, the correct answer is option A
