Assertion: In an organism, male gametes are always produced in large number as compared to female gametes.
Reason: Male gametes have to cover a reasonable distance to reach the female gametes.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
B. If both Assertion and Reason are true and the Reason is not the correct explanation of the Assertion.
C. If Assertion is true but the Reason is false.
D. If both Assertion and Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that male gametes are produced in larger numbers compared to female gametes. This is generally true across many organisms, including humans.

2. **Understanding the Reason**:
- The reason provided is that male gametes need to cover a reasonable distance to reach the female gametes. This is also accurate since male gametes (sperm) are motile and must travel to fertilize the immotile female gametes (eggs).

3. **Analyzing the Motility of Gametes**:
- Male gametes (sperm) are motile, meaning they can move actively. In contrast, female gametes (eggs) are typically non-motile. This difference necessitates that a larger number of male gametes be produced to ensure that at least some can reach the egg.

4. **Example from Human Reproduction**:
- In humans, sperm must travel from the vaginal tract through the cervix and uterus to the fallopian tubes where fertilization occurs. This distance is significant, and many sperm do not survive the journey, which is why a large number are produced.

5. **Conclusion**:
- Both the assertion and the reason are true. The reason effectively explains the assertion, as the need for male gametes to travel a distance contributes to their larger production.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation for the assertion.

---