The level of organisation in Echinodermata is of

Options

A. Cellular level
B. Tissue level
C. Organ level
D. Organ-system level

Answer

### Step-by-Step Solution:

1. **Identify the Phylum**: The question asks about the level of organization in Echinodermata. Echinodermata includes marine animals such as sea urchins and starfish.

2. **Understand the Classification of Animal Organization**: Animal body organization can be classified into different levels:
- Cellular Level: Found in Porifera (sponges).
- Tissue Level: Found in Cnidaria (jellyfish) and Ctenophora (comb jellies).
- Organ Level: Found in Platyhelminthes (flatworms).
- Organ System Level: Found in higher invertebrates and vertebrates, including Echinodermata.

3. **Determine the Level of Organization in Echinodermata**: Echinoderms possess a complex body structure that includes various systems (like the water vascular system, digestive system, etc.), which indicates they have an organ system level of organization.

4. **Conclusion**: Therefore, the level of organization in Echinodermata is classified as the **organ system level**.

### Final Answer:
The level of organization in Echinodermata is of **organ system level**.

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