Which structure acts as a filter for lymph fluid?

• A. Lymph nodes
• B. Lymph trunks
• C. Blood capillaries
• D. Venous angle

Answer: (A)

Lymph nodes act as filters for lymph fluid, trapping pathogens and debris as lymph passes through and allowing immune cells like macrophages and lymphocytes to detect invaders and mount a response. This filtration happens inside the node’s sinuses, where circulating particles are scanned and destroyed if needed. The other structures serve different roles: lymph trunks transport lymph toward the venous system but don’t filter it; blood capillaries filter blood, not lymph; and the venous angle is simply a drainage point where lymph re-enters the bloodstream, not a filtering site. So the lymph node is the structure that filters lymph.