Nematocysts are found in

Options

A. Porifera
B. Coelenterata
C. Nematodes
D. Annelida

Answer

### Step-by-Step Solution:

1. **Understanding Nematocysts**: Nematocysts are specialized cells that contain a stinging structure used by certain animals for capturing prey and defense.

2. **Identifying the Relevant Phylum**: In the animal kingdom, nematocysts are primarily associated with the phylum Cnidaria, which is also known as Coelenterata.

3. **Characteristics of Cnidaria (Coelenterata)**: This phylum is characterized by the presence of stinging cells called cnidocytes, which contain nematocysts. These cells are crucial for the survival of these organisms as they help in capturing prey and providing defense against predators.

4. **Examining the Options**: The options given are:
- Porifera
- Coelenterata (Cnidaria)
- Nematodes
- Annelida

5. **Eliminating Incorrect Options**:
- **Porifera**: This phylum includes sponges, which do not have nematocysts.
- **Nematodes**: These are roundworms and do not possess nematocysts.
- **Annelida**: This phylum includes segmented worms, which also do not have nematocysts.

6. **Conclusion**: The only phylum that contains nematocysts is Coelenterata (Cnidaria). Therefore, the correct answer is Coelenterata.

### Final Answer:
Nematocysts are found in **Coelenterata (Cnidaria)**.

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