What is true about Nereis, scorpion, cockroah and silver fish?

Options

A. They all possess dorsal heart.
B. None of them is aquatic
C. They all belong to the same phylum.
D. They all have jointed paired appendages.

Explanation

To determine what is true about Nereis, scorpion, cockroach, and silverfish, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- The organisms in question are Nereis, scorpion, cockroach, and silverfish.

2. **Analyze the First Option**:
- **Dorsal Heart**: Check if all four organisms possess a dorsal heart.
- Nereis (an annelid) has a dorsal heart.
- Scorpions (arthropods) have a dorsal heart.
- Cockroaches (arthropods) also have a dorsal heart.
- Silverfish (arthropods) have a dorsal heart.
- Conclusion: All four organisms possess a dorsal heart. This option is **correct**.

3. **Analyze the Second Option**:
- **Aquatic Status**: Check if none of them are aquatic.
- Nereis is aquatic.
- Scorpions are primarily terrestrial.
- Cockroaches are terrestrial.
- Silverfish are aquatic.
- Conclusion: This option is **incorrect** because Nereis and silverfish are aquatic.

4. **Analyze the Third Option**:
- **Phylum Classification**: Check if they all belong to the same phylum.
- Nereis belongs to the phylum Annelida.
- Scorpions, cockroaches, and silverfish belong to the phylum Arthropoda.
- Conclusion: This option is **incorrect** because they do not belong to the same phylum.

5. **Analyze the Fourth Option**:
- **Joint Appendages**: Check if they all have joint paired appendages.
- Nereis has parapodia for locomotion, not joint appendages.
- Scorpions have five pairs of jointed legs.
- Cockroaches have jointed appendages.
- Silverfish have appendages but not jointed in the same way.
- Conclusion: This option is **incorrect** because Nereis does not have joint paired appendages.

6. **Final Conclusion**:
- The only true statement about Nereis, scorpion, cockroach, and silverfish is that they all possess a dorsal heart.

### Final Answer:
They all possess a dorsal heart.