Arms do not occur in

Options

A. Sea Urchin
B. Sea Cucumber
C. Both A and B
D. Sea star.

Answer

To solve the question "Arms do not occur in," we will analyze the options provided and determine which organisms lack arms.

### Step-by-Step Solution:

1. **Identify the Organisms**: The options given are:
- A. Sea Urchin
- B. Sea Cucumber
- C. Both A and B
- D. Sea Star (Starfish)

2. **Analyze Sea Urchin**:
- Sea urchins have a globular body covered with spines but do not have distinct arms. They move using their spines and tube feet.
- Conclusion: Sea Urchin does not have arms.

3. **Analyze Sea Cucumber**:
- Sea cucumbers have an elongated, cylindrical body. They do not possess arms; instead, they have tentacles around their mouth, which are not considered arms.
- Conclusion: Sea Cucumber also does not have arms.

4. **Evaluate Both A and B**:
- Since both Sea Urchin and Sea Cucumber do not have arms, option C (Both A and B) is a valid choice.

5. **Analyze Sea Star (Starfish)**:
- Sea stars are characterized by having five or more arms extending from their central disc. Therefore, they do have arms.
- Conclusion: Sea Star cannot be the answer.

6. **Final Answer**:
- Since both Sea Urchin and Sea Cucumber do not have arms, the correct answer is option C: Both A and B.

### Final Answer:
**C. Both A and B (Sea Urchin and Sea Cucumber)**

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