Arms are abuent in

Options

A. Feather Star
B. Brittle Star
C. Star Fish
D. Sea Dollar.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which of the given options does not have arms. We need to identify the organism that is known to lack arms.

2. **Analyzing the Options**: The options provided are:
- A) Feather star
- B) Brittle star
- C) Starfish
- D) Sea dollar

3. **Identifying Characteristics of Each Option**:
- **Feather Star**: This echinoderm has long, feathery arms that extend from its body.
- **Brittle Star**: This echinoderm has long, slender arms that are distinct from its central disk.
- **Starfish**: This echinoderm is characterized by its multiple arms radiating from a central body.
- **Sea Dollar**: Also known as sand dollar, this echinoderm is flat and round, lacking distinct arms.

4. **Conclusion**: Based on the characteristics analyzed, the organism that does not have arms is the **Sea Dollar** (option D).

5. **Final Answer**: Arms are absent in **Sea Dollar**.

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