Earthworm and cockroach both have

Options

A. Dorsal nerve cord
B. Unsegmented body
C. Malpighian tubule
D. Ventral nerve cord

Explanation

### Step-by-Step Solution

1. **Identify the Organisms**: The question asks about the common features of two organisms: the earthworm and the cockroach. The earthworm belongs to the genus *Ferritima* and the phylum Annelida, while the cockroach belongs to the genus *Periplaneta* and the phylum Arthropoda.

2. **Analyze the Options**: We have four options to evaluate:
- Option 1: Dorsal nerve cord
- Option 2: Unsegmented body
- Option 3: Malpighian tubules
- Option 4: Ventral nerve cord

3. **Evaluate Option 1 - Dorsal Nerve Cord**: The dorsal nerve cord is characteristic of organisms in the phylum Chordata, which have a notochord. Both earthworms and cockroaches are non-chordates, so this option is incorrect.

4. **Evaluate Option 2 - Unsegmented Body**: Earthworms exhibit metamerism, meaning they have a segmented body composed of numerous segments (typically 100-200). Cockroaches also have a segmented body divided into head, thorax, and abdomen. Therefore, this option is also incorrect.

5. **Evaluate Option 3 - Malpighian Tubules**: Malpighian tubules are excretory structures found in cockroaches. Earthworms do not have Malpighian tubules; instead, they possess nephridia for excretion. Thus, this option is incorrect as well.

6. **Evaluate Option 4 - Ventral Nerve Cord**: Both earthworms and cockroaches possess a ventral nerve cord, which is typical for invertebrates. Therefore, this option is correct.

7. **Conclusion**: The common feature between earthworms and cockroaches is the presence of a ventral nerve cord.

### Final Answer
**The correct answer is: Ventral nerve cord.**

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