In echinoderms skeleton is

Options

A. Calcareous
B. Chitinous
C. siliceous
D. Tunicin

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 unique features, including a spiny body and a water vascular system.

2. **Identifying the Skeleton Type**: The question specifically asks about the type of skeleton found in echinoderms. The options provided are:
- A) Calcareous
- B) Chitinous
- C) Siliceous
- D) Tunicin

3. **Analyzing the Options**:
- **Calcareous**: This refers to a skeleton made of calcium carbonate, which is characteristic of echinoderms.
- **Chitinous**: This type of skeleton is found in arthropods, not echinoderms.
- **Siliceous**: This is associated with organisms like sponges, not echinoderms.
- **Tunicin**: This is a component of the tunic in tunicates, unrelated to echinoderms.

4. **Conclusion**: Based on the information, echinoderms possess a calcareous skeleton. Therefore, the correct answer is option A) Calcareous.

### Final Answer:
The skeleton in echinoderms is **calcareous** (Option A).

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