Question

Select the option that contains only secondary lymphoid organs.

• A. Spleen, Tonsils, Thymus
• B. Lymph nodes, Appendix, Tonsils
• C. Peyer's patches, Tonsils, Bone marrow
• D. Tonsils, Thymus, Lymph nodes

Hint:

To solve quickly, just remember the 2 Primary organs: Bone Marrow and Thymus. Any option containing either of these is immediately incorrect for a "secondary only" question.

Answer 1

The Correct Option is B

Step 1: Understanding the Problem:
The human immune system features lymphoid organs which are categorized into primary and secondary. Primary organs are sites of lymphocyte origin and maturation, while secondary organs are sites where lymphocytes interact with antigens.
Step 2: Approach and Formula:
Filter the options by identifying and eliminating any group that contains a primary lymphoid organ (Bone marrow or Thymus).
Step 3: Detailed Explanation:
- Primary lymphoid organs include the Bone marrow and the Thymus.
- Secondary lymphoid organs include the Spleen, Lymph nodes, Tonsils, Peyer's patches of the small intestine, and the Appendix.
- Option (1) contains Thymus (Primary) $\rightarrow$ Incorrect.
- Option (3) contains Bone marrow (Primary) $\rightarrow$ Incorrect.
- Option (4) contains Thymus (Primary) $\rightarrow$ Incorrect.
- Option (2) contains Lymph nodes, Appendix, and Tonsils, all of which are exclusively secondary lymphoid organs.
Step 4: Final Answer:
The correct option is (2).