Earthworm are

Options

A. ureotellic when plenty of water is available
B. uricotelic when plenty of water is available
C. uricotelic under conditions of water scarcity
D. ammonotelic when plenty of water is available

Answer

### Step-by-Step Solution:

1. **Understanding Earthworm's Habitat**:
- Earthworms are terrestrial organisms, meaning they live on land. This habitat influences their excretory processes.

2. **Identifying the Phylum**:
- Earthworms belong to the phylum Annelida. This classification is important as it helps us understand their biological processes, including excretion.

3. **Excretory Products in Different Water Conditions**:
- When there is plenty of water available, earthworms primarily excrete ammonia. Ammonia is a toxic waste product that requires a lot of water to be safely eliminated from the body.
- In conditions of water scarcity, earthworms switch to a different excretory method. They become ureotelic, meaning they excrete urea instead of ammonia. Urea is less toxic and requires less water for excretion.

4. **Analyzing the Options**:
- **Option 1**: Ureotelic when plenty of water is available - **Incorrect** (they are ammonotelic).
- **Option 2**: Uricotelic when plenty of water is available - **Incorrect** (they are ammonotelic).
- **Option 3**: Uricotelic under conditions of water scarcity - **Incorrect** (they are ureotelic, not uricotelic).
- **Option 4**: Ammonotelic when plenty of water is available - **Correct** (this accurately describes their excretory method in high water conditions).

5. **Conclusion**:
- The correct answer to the question is that earthworms are **ammonotelic** when plenty of water is available.