Identify the set of secondary lymphoid organs from the followings:

Options

A. Bone marrow and lymph nodes
B. Spleen and bone marrow
C. Bone marrow and thyms gland
D. Spleen and lymph nodes

Answer

To identify the set of secondary lymphoid organs from the given options, we need to understand the distinction between primary and secondary lymphoid organs.

### Step-by-Step Solution:

1. **Understand Lymphoid Organs**: Lymphoid organs are specialized tissues where lymphocytes (a type of immune cell) mature and function. They are crucial for the immune response.

2. **Differentiate Between Primary and Secondary Lymphoid Organs**:
- **Primary Lymphoid Organs**: These are the sites where lymphocytes are produced and mature. The primary lymphoid organs include:
- Bone marrow
- Thymus gland
- **Secondary Lymphoid Organs**: These are the sites where lymphocytes are activated and carry out their immune functions. The secondary lymphoid organs include:
- Spleen
- Lymph nodes

3. **Analyze the Options**:
- **Option 1**: Bone marrow and lymph nodes - Bone marrow is a primary lymphoid organ.
- **Option 2**: Spleen and bone marrow - Bone marrow is a primary lymphoid organ.
- **Option 3**: Bone marrow and thymus gland - Both are primary lymphoid organs.
- **Option 4**: Thymus gland and spleen - Thymus is a primary lymphoid organ.

4. **Identify the Correct Option**: The only option that contains exclusively secondary lymphoid organs is:
- **Spleen and lymph nodes** (This is the correct answer).

### Conclusion:
The correct set of secondary lymphoid organs from the options provided is **spleen and lymph nodes**.

---