Which is amphibious?

Options

A. Casuarina
B. Wolffia
C. Polygonum
D. Hydrilla.

Answer

### Step-by-Step Solution:

1. **Understanding the Term "Amphibious":**
- The term "amphibious" refers to organisms that can thrive in both terrestrial (land) and aquatic (water) environments. This means they can grow and survive in both settings.

2. **Analyzing the Options:**
- The options provided are:
- Catherina
- Wolffia
- Polygonum
- Hydrilla

3. **Evaluating Each Option:**
- **Catherina:** This plant is primarily terrestrial and does not grow in water.
- **Wolffia:** This is a genus of tiny aquatic plants that float on water and do not grow on land.
- **Hydrilla:** This is an aquatic plant that grows underwater and does not thrive on land.
- **Polygonum:** This plant is known to be amphibious, meaning it can grow both on land and in water.

4. **Conclusion:**
- Among the given options, **Polygonum** is the only amphibious plant that can grow in both environments.

### Final Answer:
The amphibious plant among the given options is **Polygonum**.

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