Paedogenesis is observed in

Options

A. (a) Ctenophores
B. (b) Liver fluke
C. (c) Both Ctenophores and Liver Fluke
D. (d) Ascaris

Answer

### Step-by-Step Solution:

1. **Understanding Paedogenesis**:
- Paedogenesis is a form of reproduction that occurs in the larval stage of certain organisms. It allows larvae to reproduce while still in their immature form, without undergoing metamorphosis.

2. **Characteristics of Paedogenesis**:
- In paedogenesis, the larvae are sexually mature and can reproduce without fertilization. This adaptation is often seen in response to stressful environmental conditions.

3. **Identifying Organisms that Exhibit Paedogenesis**:
- Paedogenesis is primarily observed in certain invertebrates, particularly in the phylum **Cnidaria** and **Tunicata**, but it is also noted in some members of the phylum **Ctenophora** (commonly known as comb jellies).

4. **Analyzing the Options**:
- **Option A: Tenophores**: This is a correct option as paedogenesis is known to occur in this phylum.
- **Option B: Liver Fluke**: This organism belongs to the phylum **Platyhelminthes**, where paedogenesis does not occur.
- **Option C: Ascaris**: This organism belongs to the phylum **Nematoda** (roundworms), and paedogenesis is not observed here either.

5. **Conclusion**:
- Based on the analysis, the correct answer to the question "Paedogenesis is observed in" is **Option A: Tenophores**.