Which of the following group of animals reproduces only by sexual means?

Options

A. Ctenophora
B. Cnidaria
C. Porifera
D. Protozoa

Answer

To determine which group of animals reproduces only by sexual means, we can analyze the reproductive methods of various animal groups mentioned in the transcript.

### Step-by-Step Solution:

1. **Identify the Groups of Animals**: The transcript mentions several groups:
- Tinophora
- Neidheria
- Polyphera
- Protozoa

2. **Analyze Reproduction in Each Group**:
- **Tinophora**: The transcript states that Tinophora does not have an asexual phase and reproduces only through sexual means. This group is confirmed to reproduce solely by sexual reproduction.
- **Neidheria**: This group has both asexual forms (polyp and medusa) and thus does not reproduce solely by sexual means.
- **Polyphera**: This group is noted to reproduce asexually through methods like budding and fragmentation, indicating that it does not reproduce only by sexual means.
- **Protozoa**: Protozoa are also mentioned to reproduce asexually through budding and fragmentation, confirming that they do not reproduce solely by sexual means.

3. **Conclusion**: Based on the analysis, the only group that reproduces exclusively by sexual means is **Tinophora**.

### Final Answer:
The group of animals that reproduces only by sexual means is **Tinophora**.

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