Which one of the following features is common to cockroach, earthworm and mosquito?

Options

A. Presence of chitinous exoskeleton
B. Presence of jointed appendages
C. Presence of two pair of wings
D. Presence of schizocoelom as a true coelom

Answer

To solve the question regarding the common feature among cockroach, earthworm, and mosquito, we need to analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- Cockroach (Phylum: Arthropoda)
- Earthworm (Phylum: Annelida)
- Mosquito (Phylum: Arthropoda)

2. **Analyze Each Option**:
- **Option 1: Presence of Chitinous Exoskeleton**:
- Cockroach and mosquito have a chitinous exoskeleton (characteristic of arthropods), but earthworms do not have an exoskeleton as they belong to Annelida.
- **Conclusion**: Incorrect.

- **Option 2: Presence of Jointed Appendages**:
- Jointed appendages are a characteristic feature of arthropods (found in cockroach and mosquito) but are not present in earthworms.
- **Conclusion**: Incorrect.

- **Option 3: Presence of Two Pairs of Wings**:
- This feature is specific to certain insects (like mosquitoes) but not applicable to earthworms or cockroaches (which have one pair of wings).
- **Conclusion**: Incorrect.

- **Option 4: Presence of Schizocoelom as a True Coelom**:
- Both arthropods (like cockroaches and mosquitoes) and annelids (like earthworms) possess a true coelom formed by the splitting of mesoderm, known as schizocoelom.
- **Conclusion**: Correct.

3. **Final Answer**: The common feature among cockroach, earthworm, and mosquito is the **presence of schizocoelom as a true coelom**.