Assertion: Sexual reproduction of Spirogyra is isogamous type.
Reason: Both of the fusing gametes of Spirogyra are nonglagellated and similar in size.

Options

A. If both assertion and Reason are true and the reason is a correct explanation of the assertion.
B. If both Assertion and Reason are true but Reason is not a 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 Terms**:
- **Assertion**: The statement claims that the sexual reproduction of Spirogyra is isogamous.
- **Reason**: The statement explains that both fusing gametes of Spirogyra are non-flagellated and similar in size.

2. **Identifying Spirogyra**:
- Spirogyra is a type of green algae that belongs to the division Chlorophyceae. It is characterized by its spiral chloroplasts and is known for its ability to reproduce both sexually and asexually.

3. **Types of Sexual Reproduction in Algae**:
- There are three main types of sexual reproduction in algae:
- **Isogamous**: Both male and female gametes are similar in size and shape.
- **Anisogamous**: Male and female gametes are dissimilar in size and shape.
- **Oogamous**: Male gamete is smaller and motile, while the female gamete is larger and non-motile.

4. **Analyzing the Assertion**:
- The assertion states that Spirogyra reproduces sexually in an isogamous manner. This is correct because in Spirogyra, the gametes are indeed similar in size and shape.

5. **Analyzing the Reason**:
- The reason states that both fusing gametes are non-flagellated and similar in size. This is also correct, as Spirogyra's gametes do not have flagella and are indistinguishable from one another.

6. **Conclusion**:
- Since both the assertion and the reason are correct, and the reason provides a valid explanation for the assertion, we conclude that both statements are true and the reason is a correct explanation of the assertion.

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

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