Which of the following is the most distinctive feature of echinodermata ?

Options

A. Presence of larva
B. Organ system level of body organization
C. Presence of water vascular system
D. All of these

Answer

To determine the most distinctive feature of Echinodermata, we can follow these steps:

### Step 1: Understand the options provided
The options given are:
1. Presence of larva
2. Organ system
3. Level of body organization
4. Presence of water vascular system
5. All of these

### Step 2: Analyze each option
- **Presence of larva**: Many animal groups, not just Echinodermata, have larval stages. Therefore, this is not unique to Echinodermata.
- **Organ system**: Echinoderms have organ systems, but so do many other animal phyla. This feature is not distinctive.
- **Level of body organization**: Echinoderms exhibit a level of body organization that is also seen in other groups, so this is not a unique characteristic.
- **Presence of water vascular system**: This is a unique feature of Echinodermata. The water vascular system is a hydraulic system used for locomotion, feeding, and waste transportation, which is not found in other animal groups.

### Step 3: Identify the correct answer
Given the analysis, the most distinctive feature of Echinodermata is the **presence of a water vascular system**.

### Conclusion
The correct answer to the question is **presence of water vascular system**.

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