Which structure filters foreign particles and contains white blood cells?

• A. Bone marrow
• B. Lymph nodes
• C. Spleen
• D. Thymus

Answer: (B)

Verified step by step guidance

1. Begin by understanding the primary function of each structure listed in the problem. Bone marrow is responsible for producing blood cells, including white blood cells, but it does not filter foreign particles.
2. Next, consider the role of the spleen. The spleen filters blood, removing old or damaged red blood cells and foreign particles, and it also contains white blood cells. However, its primary function is not filtering foreign particles from lymph.
3. Examine the thymus. The thymus is involved in the maturation of T lymphocytes (a type of white blood cell) but does not filter foreign particles.
4. Focus on lymph nodes. Lymph nodes are small, bean-shaped structures that filter lymph fluid, trapping foreign particles such as bacteria and viruses. They contain white blood cells, particularly lymphocytes, which help in the immune response.
5. Conclude that lymph nodes are the correct answer because they are specifically designed to filter foreign particles from lymph and contain white blood cells to combat infections.