Assertion : Euglena possesses characteristics of both plant and animal.
Reason : Euglena is a genus of unicellular protist.

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.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Euglena possesses characteristics of both plant and animal." This means that Euglena exhibits traits that are typically found in both plants and animals.

2. **Understanding the Reason**: The reason provided is that "Euglena is a genus of unicellular protist." This indicates that Euglena belongs to the kingdom Protista, which includes unicellular organisms.

3. **Analyzing Euglena's Characteristics**:
- Euglena can perform photosynthesis when sunlight is available, which is a characteristic of plants (autotrophic nutrition).
- In the absence of sunlight, Euglena can consume organic matter from its environment, resembling the behavior of animals (heterotrophic nutrition).

4. **Conclusion on the Assertion**: Since Euglena can exhibit both autotrophic and heterotrophic modes of nutrition, it indeed possesses characteristics of both plants and animals, supporting the assertion.

5. **Conclusion on the Reason**: The reason correctly identifies Euglena as a unicellular protist, but it does not explain why Euglena has both plant and animal characteristics. It simply states its classification without linking it to the assertion.

6. **Final Evaluation**: Both the assertion and reason are correct statements, but the reason does not adequately explain the assertion. Therefore, the correct conclusion is that both statements are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
- **Both the assertion and the reason are correct, but the reason is not the correct explanation for the assertion.**