In the following question a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :
Assertion (A): Bone marrow and thymus are primary lymphoid organs.
Reason(R): It is the organs, to which matured lymphocytes migrate, interact with antigens and then proliferate to become effector cells.

Options

A. Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
B. Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
C. Assertion (A) is true but reason (R) is false.
D. Assertion (A) is false but reason (R) is true.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion (A):** The assertion states that "Bone marrow and thymus are primary lymphoid organs." This is a true statement. Bone marrow is responsible for the production of blood cells, including lymphocytes, while the thymus is where T-lymphocytes mature.

2. **Understanding the Reason (R):** The reason provided states, "It is the organs, to which matured lymphocytes migrate, interact with antigens and then proliferate to become effector cells." This statement is misleading because it describes the function of secondary lymphoid organs, such as lymph nodes and spleen, where mature lymphocytes interact with antigens.

3. **Evaluating the Relationship:** Since the assertion is true and the reason is false, we can conclude that the reason does not correctly explain the assertion.

4. **Selecting the Correct Option:** Based on the evaluation:
- The assertion is true.
- The reason is false.
Therefore, the correct choice is that the assertion is true, but the reason is false.

**Final Answer:** The assertion is true, but the reason is false.

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