Given below are assertion and reason. Point out if both are correct with reason being true explanation (A), both correct but reason is not true explanation (B), assertion correct Assertion upto ovulation oocyte has released one polar body. Reason, Released oocyte in the fallopian tube is in secondary metaphase stage.

Options

A. A
B. B
C. C
D. D

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "up to ovulation, the oocyte has released one polar body." This refers to the process of oocyte maturation.

2. **Oocyte Development**: During oocyte development, the primary oocyte undergoes meiosis. It completes the first meiotic division just before ovulation, resulting in a secondary oocyte and a polar body.

3. **Polar Body Formation**: The polar body is a small cell that is a byproduct of the meiotic division and does not develop into an egg. Therefore, the assertion is correct as it indicates that one polar body is released during this process.

4. **Understanding the Reason**: The reason states that "the released oocyte in the fallopian tube is in the secondary metaphase stage." This is also true. After ovulation, the secondary oocyte is arrested in metaphase II of meiosis until fertilization occurs.

5. **Evaluating the Relationship**: While both the assertion and the reason are correct, the reason does not directly explain the assertion. The assertion talks about the release of the polar body, while the reason discusses the stage of the oocyte in the fallopian tube.

6. **Conclusion**: Since both statements are correct but the reason does not provide a true explanation for the assertion, the correct option is (B) - both are correct, but the reason is not a true explanation.

### Final Answer:
**Option B**: Both are correct, but the reason is not a true explanation.