Differentiation in segmental fashion occurs in

Options

A. Leech
B. Starfish
C. Snails
D. Ascaris

Explanation

**Step-by-Step Solution:**

1. **Understand the Question**: The question asks about which organism shows differentiation in a segmental fashion. This refers to the way the body is divided into segments, which can have specialized functions.

2. **Identify the Options**: The options given are:
- Leeches
- Starfish
- Snail
- Ascaris

3. **Analyze Each Option**:
- **Leeches**: Leeches belong to the phylum Annelida. Annelids exhibit metameric segmentation, meaning their bodies are divided into segments that are similar and contain organs. This is a clear indication of differentiation in a segmental fashion.
- **Starfish**: Starfish belong to the phylum Echinodermata. They do not exhibit metameric segmentation; instead, they have a radial symmetry and spines, which is not related to segmental differentiation.
- **Snail**: Snails belong to the phylum Mollusca. Their defining feature is the presence of a shell, and they do not show metameric segmentation.
- **Ascaris**: Ascaris is a roundworm that belongs to the phylum Nematoda (not Asclementes as mentioned). Nematodes do not exhibit metameric segmentation; they have a cylindrical body shape.

4. **Conclusion**: Since only leeches (annelids) exhibit metameric segmentation, the correct answer is **Leeches**.

5. **Final Answer**: The differentiation in segmental fashion occurs in **Leeches** (Option 1).

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