Presence of nematocysts is a characteristic feature of the phylum :

Options

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

Explanation

To solve the question regarding the presence of nematocysts and identify the correct phylum, follow these steps:

### Step-by-Step Solution:

1. **Understanding Nematocysts**:
- Nematocysts are specialized cells that contain a stinging structure. They are primarily used for capturing prey and defense against predators.

2. **Identifying Organisms with Nematocysts**:
- Nematocysts are commonly found in certain marine organisms, particularly in jellyfish and other members of the phylum Cnidaria.

3. **Phylum Identification**:
- The question provides four phyla, and we need to determine which one is characterized by the presence of nematocysts.
- The phylum Cnidaria (previously referred to as Coelenterata) includes organisms such as jellyfish, corals, and sea anemones, all of which possess nematocysts.

4. **Conclusion**:
- Since nematocysts are a defining feature of the phylum Cnidaria, the correct answer to the question is that the presence of nematocysts is a characteristic feature of the phylum **Cnidaria**.

### Final Answer:
The presence of nematocysts is a characteristic feature of the phylum **Cnidaria**.