Assertion: Aquatic plants contain aerenchyma.
Reason: Aerenchyma keeps aquatic plants afloat.

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.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that aquatic plants contain aerenchyma. Aerenchyma is a specialized type of parenchyma tissue that has large air spaces, which is commonly found in aquatic plants.

2. **Identifying Aquatic Plants**: Aquatic plants, also known as hydrophytes, are plants that live in water, either fully submerged or partially submerged. They have adaptations that allow them to thrive in such environments.

3. **Function of Aerenchyma**: Aerenchyma serves multiple functions in aquatic plants. One of its primary roles is to facilitate the transport of gases, particularly oxygen, during photosynthesis. The large air spaces allow for the diffusion of gases throughout the plant.

4. **Buoyancy and Floating**: The presence of aerenchyma provides buoyancy to aquatic plants. This buoyancy is crucial because it helps keep the plants afloat on the water's surface. For example, the inflated petioles of plants like *Eichhornia* (water hyacinth) allow them to remain buoyant.

5. **Evaluating the Reason**: The reason states that aerenchyma keeps aquatic plants afloat. Since aerenchyma provides the necessary buoyancy due to its air-filled spaces, this statement is correct.

6. **Conclusion**: Both the assertion and the reason are correct. Furthermore, the reason provides a valid explanation for the assertion, as aerenchyma indeed helps aquatic plants to float.

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

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