Metagenesis is found in

Options

A. Obelia
B. Hydra
C. Tubipora
D. Metridium

Answer

### Step-by-Step Solution:

1. **Understanding Metagenesis**:
- Metagenesis refers to the alternation of generations between sexual and asexual reproduction in an organism. This means that an organism can reproduce both sexually and asexually in different life stages.

2. **Identifying Organisms**:
- The question provides several options to consider: Obelia, Hydra, Tubipora, and Metridium. We need to analyze each one to see if they exhibit metagenesis.

3. **Analyzing Obelia**:
- Obelia belongs to the class Hydrozoa. It exhibits both polyp and medusa forms.
- The polyp stage is associated with asexual reproduction, while the medusa stage is associated with sexual reproduction.
- Since Obelia can reproduce both sexually and asexually, it demonstrates metagenesis.

4. **Analyzing Hydra**:
- Hydra also belongs to the class Hydrozoa but primarily reproduces asexually through budding.
- It does not have a medusa stage or sexual reproduction. Therefore, metagenesis is not present in Hydra.

5. **Analyzing Tubipora**:
- There is limited information available about Tubipora's mode of reproduction.
- Without clear evidence of both sexual and asexual reproduction, we cannot conclude that metagenesis occurs in Tubipora.

6. **Analyzing Metridium**:
- Metridium, which is a sea anemone, primarily reproduces asexually.
- Similar to Hydra, it does not exhibit sexual reproduction, so metagenesis is not possible in Metridium.

7. **Conclusion**:
- Based on the analysis, the only organism that exhibits metagenesis is Obelia. Therefore, the correct answer is Obelia.

### Final Answer:
Metagenesis is found in **Obelia**.

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