In which of the following moulting is not found ?

Options

A. Hydra
B. Mosquito
C. Housefly
D. Cockroach

Answer

To solve the question "In which of the following moulting is not found?" we will analyze each option provided.

### Step-by-Step Solution:

1. **Understand the concept of moulting**: Moulting is the process of shedding the outer skin or exoskeleton. It is a common phenomenon in certain animal groups, particularly in insects, crustaceans, and some reptiles.

2. **Analyze the options**: The options given are:
- Hydra
- Mosquito
- Housefly
- Cockroach

3. **Identify which groups the options belong to**:
- **Hydra**: This organism is a cnidarian and belongs to the class Cnidaria. Cnidarians do not undergo moulting.
- **Mosquito**: This is an insect and belongs to the class Insecta. Mosquitoes undergo moulting.
- **Housefly**: This is also an insect and belongs to the class Insecta. Houseflies undergo moulting.
- **Cockroach**: This is another insect and belongs to the class Insecta. Cockroaches undergo moulting as well.

4. **Determine which option does not exhibit moulting**: From the analysis, we see that Hydra does not undergo moulting, while the other three options (mosquito, housefly, and cockroach) do.

5. **Conclusion**: The correct answer to the question is **Hydra**, as it is the only organism listed that does not exhibit the process of moulting.

### Final Answer:
Hydra