In echinoderms, the nervous system is

Options

A. Well developed
B. With large brain
C. Devoid of brain
D. Both A and B.

Answer

**Step-by-Step Solution:**

1. **Understanding Echinoderms**: Echinoderms are a group of marine animals that include starfish, sea urchins, and sea cucumbers. They are known for their radial symmetry and unique water vascular system.

2. **Nervous System Characteristics**: The nervous system of echinoderms is not centralized like that of vertebrates. Instead, they have a decentralized nervous system.

3. **Evaluating the Options**:
- **Option A: Well Developed**: This option is incorrect. While the nervous system is complex, it is not considered well developed compared to other animal groups.
- **Option B: With Large Brain**: This option is also incorrect. Echinoderms do not possess a central brain.
- **Option C: Devoid of Brain**: This is the correct option. Echinoderms lack a central brain and instead have a network of nerves known as a nerve plexus.
- **Option D: Both A and B**: This option is incorrect for the same reasons mentioned above.

4. **Conclusion**: The correct answer is that echinoderms are devoid of a brain, having a decentralized nervous system with a nerve plexus running under the skin.

**Final Answer**: Devoid of brain.

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