Deuterostomes are

Options

A. Platyhelminthes
B. Echinodermata
C. Arthropoda
D. Annelida

Explanation

To answer the question "Deuterostomes are:", we need to understand what deuterostomes are and identify which of the given options belong to this category.

### Step-by-Step Solution:

1. **Definition of Deuterostomes**:
- Deuterostomes are a group of animals characterized by their embryonic development. In these organisms, the anus develops from the blastopore (the first opening that forms during embryonic development), while the mouth develops later.

2. **Identifying the Options**:
- The options provided are:
- A) Platyhelminthes
- B) Echinodermata
- C) Arthropoda
- D) Annelida

3. **Analyzing Each Option**:
- A) **Platyhelminthes**: These are flatworms and are classified as protostomes, not deuterostomes.
- B) **Echinodermata**: This phylum includes starfish and sea urchins, and they are indeed classified as deuterostomes.
- C) **Arthropoda**: This is the largest phylum and includes insects and crustaceans, which are protostomes.
- D) **Annelida**: This phylum includes segmented worms, which are also protostomes.

4. **Conclusion**:
- Based on the definitions and classifications, the only phylum from the options that is classified as deuterostomes is **Echinodermata**. Therefore, the answer to the question is option B) Echinodermata.

### Final Answer:
Deuterostomes are represented by the phylum **Echinodermata**.

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