The largest nematocysts of Hydra are

Options

A. Volvents
B. Penetrants
C. Atrichous isorhizas
D. Holotrichous isorhizas.

Answer

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks about the largest type of nematocysts found in Hydra. Nematocysts are specialized cells that contain stinging structures, characteristic of organisms in the phylum Cnidaria.

2. **Identify Types of Nematocysts**: There are several types of nematocysts present in Hydra, including:
- Penetrants
- Volvents
- Atrichous isorhizas
- Holotrichous isorhizas

3. **Analyze the Characteristics**: Among these types, it is important to note their size and function:
- **Penetrants**: These are typically the largest nematocysts and are used for penetrating prey.
- **Volvents**: These are smaller and primarily used for capturing prey.
- **Atrichous isorhizas** and **Holotrichous isorhizas**: These are also smaller compared to penetrants.

4. **Conclusion**: Based on the characteristics and sizes of the nematocysts, it is clear that the largest nematocysts in Hydra are the **Penetrants**.

5. **Final Answer**: Therefore, the correct answer to the question is **Penetrants**.

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