Examples of primary lymphoid organ is:

Options

A. Thymus
B. Appendix
C. Spleen
D. Tonsil

Answer

To solve the question about examples of primary lymphoid organs, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Lymphoid Organs**:
- Lymphoid organs are specialized organs where lymphocytes (a type of white blood cell) originate, grow, and mature.

2. **Identify the Types of Lymphoid Organs**:
- Lymphoid organs are classified into two categories: primary lymphoid organs and secondary lymphoid organs.
- Primary lymphoid organs are where lymphocytes are produced and mature.
- Secondary lymphoid organs are where lymphocytes are activated and proliferate.

3. **List the Primary Lymphoid Organs**:
- The primary lymphoid organs include:
- Thymus
- Bone marrow

4. **Analyze the Options Provided**:
- The options given in the question are:
A. Thymus
B. Appendix
C. Spleen
D. Tonsil
- From the list of primary lymphoid organs, we can see that the thymus is included.

5. **Determine the Correct Answer**:
- Among the options, the only primary lymphoid organ listed is the thymus (Option A).
- The appendix, spleen, and tonsils are classified as secondary lymphoid organs.

6. **Conclusion**:
- Therefore, the correct answer to the question is **Option A: Thymus**.