Radiata includes

Options

A. Nematodes
B. Nemerteans
C. Cnidaria
D. All the above.

Answer

### Step-by-Step Solution

1. **Understanding Radiata**: Radiata refers to a group of organisms that exhibit radial symmetry. This means that if the organism is divided along any plane, the resulting halves will be mirror images of each other.

2. **Identifying the Phyla Included in Radiata**: The main phyla included in the Radiata are:
- **Cnidaria**: This phylum includes organisms such as jellyfish, corals, and sea anemones, which exhibit radial symmetry.
- **Ctenophora**: This phylum includes comb jellies, which also display radial symmetry.

3. **Evaluating the Options**:
- **Option 1: Nematodes**: Nematodes belong to the phylum Nematoda and exhibit bilateral symmetry, not radial symmetry. Therefore, this option is incorrect.
- **Option 2: Nemertians**: Nemertians, or ribbon worms, belong to their own phylum and also do not exhibit radial symmetry. Thus, this option is also incorrect.
- **Option 3: Cnidaria**: As mentioned earlier, Cnidaria includes organisms that exhibit radial symmetry. This option is correct.
- **Option 4: All of the above**: Since the first two options are incorrect, this option cannot be true.

4. **Conclusion**: The only correct answer is **Cnidaria**, as it is the only group listed that is included in Radiata.

### Final Answer
**Radiata includes: Cnidaria.**

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