Echinoderms are characterised by
(a) Exclusively marine habitat and calcareous endoskeleton
(b) Presence of water vascular system and tube feet for locomotion
(c) Bilateral symmetry in larvae and radial symmetry in adults
(d) All of these

Options

A. Exclusively marine habitat and calcareous endoskeleton
B. Presence of water vascular system and tube feet for locomotion
C. Bilateral symmetry in larvae and radial symmetry in adults
D. All of these

Answer

To solve the question regarding the characteristics of Echinoderms, we will analyze each option provided and determine if they are correct.

### Step-by-Step Solution:

1. **Understanding Echinoderms**:
- Echinoderms belong to the phylum Echinodermata. Common examples include starfish and sea cucumbers.

2. **Analyzing Option A**:
- **Statement**: "Exclusively marine habitat and calcareous endoskeleton."
- **Evaluation**: Echinoderms are indeed exclusively found in marine environments and possess a calcareous endoskeleton. This statement is correct.

3. **Analyzing Option B**:
- **Statement**: "Presence of water vascular system and tube feet for locomotion."
- **Evaluation**: Echinoderms have a unique water vascular system that aids in locomotion and feeding, and they utilize tube feet for movement. This statement is also correct.

4. **Analyzing Option C**:
- **Statement**: "Bilateral symmetry in larvae and radial symmetry in adults."
- **Evaluation**: Echinoderm larvae exhibit bilateral symmetry, while adults display radial symmetry. This statement is correct as well.

5. **Analyzing Option D**:
- **Statement**: "All of these."
- **Evaluation**: Since options A, B, and C are all correct, option D, which states "All of these," is also correct.

### Conclusion:
The correct answer is **(d) All of these**, as all the statements about Echinoderms are accurate.

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