The phenomenon of metagenesis occur in

Options

A. Taenia
B. Aurelia
C. Obelia
D. Musca

Answer

### Step-by-Step Solution:

1. **Understanding Metagenesis**: Metagenesis is a biological phenomenon where an organism alternates between two different forms or generations during its life cycle. This often includes both asexual and sexual reproduction.

2. **Identifying Key Terms**: The process of metagenesis is also known as "Alteration of Generations." This means that one generation reproduces asexually while the next generation reproduces sexually.

3. **Analyzing the Options**: We have four options to consider:
- Tenia
- Aurelia
- Obelia
- Musca

4. **Evaluating Each Option**:
- **Tenia**: This is a genus of parasitic flatworms and does not exhibit metagenesis.
- **Aurelia**: This is a genus of jellyfish that also does not show a clear alternation of generations in the same way as metagenesis.
- **Obelia**: This organism is known for its life cycle that includes both asexual and sexual reproduction, demonstrating clear metagenesis.
- **Musca**: This is a genus of flies and does not exhibit metagenesis.

5. **Conclusion**: Based on the analysis, the correct answer is **C. Obelia**, as it is the only option that demonstrates the phenomenon of metagenesis through its alternating generations of asexual and sexual reproduction.