Assertion: XX-XY type of sex determination mechanism is an example of male heterogamety.
Reason: In birds, male heterogamety is seen as males produce two different types of gametes.

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that the XX-XY type of sex determination mechanism is an example of male heterogamety. In this system, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). Since males produce two different types of gametes (X and Y), this indeed represents male heterogamety.

2. **Understanding the Reason**: The reason provided states that in birds, male heterogamety is seen as males produce two different types of gametes. However, in birds, the sex determination system is different. In birds, males are homogametic (ZZ), while females are heterogametic (ZW). This means that the males do not produce two different types of gametes; they produce only one type (Z).

3. **Evaluating the Assertion and Reason**: The assertion is correct because the XX-XY system does represent male heterogamety. However, the reason is incorrect because it misrepresents the sex determination system in birds. In birds, it is the females that are heterogametic, not the males.

4. **Conclusion**: Since the assertion is true and the reason is false, the correct answer is that the assertion is correct, but the reason is incorrect.

### Final Answer:
- The assertion is true, and the reason is false.