Metameric segmentation is the characteristic of

Options

A. Mollusca and chordata
B. Platyhelminthes and Arthropoda
C. Echinodermata and Annelida
D. Annelida and Arthropoda

Answer

**Step-by-Step Solution:**

1. **Understand the Concept of Metameric Segmentation:**
- Metameric segmentation refers to the division of an organism's body into repeated segments or parts. Each segment contains similar organs and tissues.

2. **Analyze the Options:**
- The question provides four options:
1. Mollusca and Chordata
2. Platyhelminthes and Arthropods
3. Echinodermata and Annelida
4. Annelida and Arthropoda

3. **Evaluate Option 1 (Mollusca and Chordata):**
- Mollusca are invertebrates and do not exhibit segmentation.
- Chordata may show metameric segmentation in early embryonic stages, but this is not present in adults.
- Therefore, this option is incorrect.

4. **Evaluate Option 2 (Platyhelminthes and Arthropods):**
- Platyhelminthes (flatworms) do not exhibit metameric segmentation.
- Arthropods (like cockroaches) do show metameric segmentation.
- Since one of the groups does not exhibit segmentation, this option is also incorrect.

5. **Evaluate Option 3 (Echinodermata and Annelida):**
- Echinodermata (like starfish) do not exhibit metameric segmentation.
- Annelida (segmented worms) do show both internal and external metameric segmentation.
- Since one of the groups does not exhibit segmentation, this option is incorrect.

6. **Evaluate Option 4 (Annelida and Arthropoda):**
- Annelida shows both internal and external metameric segmentation.
- Arthropoda also exhibits metameric segmentation.
- Since both groups show metameric segmentation, this option is correct.

7. **Conclusion:**
- The correct answer is Option 4: Annelida and Arthropoda, as both exhibit metameric segmentation.

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