Which of the following is a deuterostome?

Options

A. Snail
B. Octopus
C. Sea star
D. Earthworm

Explanation

To determine which of the following organisms is a deuterostome, we can follow these steps:

### Step 1: Understand the Definition of Deuterostomes
Deuterostomes are a group of animals characterized by their embryonic development. In deuterostomes, the first opening that forms during embryonic development becomes the anus, while the mouth develops later. This is in contrast to protostomes, where the mouth forms first.

### Step 2: Identify the Organisms Given in the Options
The options provided are:
1. Snail
2. Octopus
3. Sea star
4. Earthworm

### Step 3: Classify Each Organism
- **Snail**: Snails belong to the phylum Mollusca and are classified as protostomes.
- **Octopus**: Octopuses also belong to the phylum Mollusca and are classified as protostomes.
- **Sea star**: Sea stars belong to the phylum Echinodermata, which are classified as deuterostomes.
- **Earthworm**: Earthworms belong to the phylum Annelida and are classified as protostomes.

### Step 4: Identify the Deuterostome
From the classification, we see that the only organism that is a deuterostome is the **sea star**.

### Conclusion
The correct answer is **option C: sea star**.

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