Which of the following is not a class of Mollusca ?

Options

A. Decapoda
B. Gastropoda
C. Scaphopoda
D. Cephalpoda

Answer

To determine which of the following is not a class of Mollusca, we can analyze the provided options: Decapoda, Gastropoda, Scaphopoda, and Cephalopoda.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are:
- Decapoda
- Gastropoda
- Scaphopoda
- Cephalopoda

2. **Understand Mollusca Classes**: Mollusca is a phylum that includes various classes. The main classes of Mollusca include:
- Gastropoda (snails and slugs)
- Scaphopoda (tusk shells)
- Cephalopoda (squids and octopuses)
- Other classes include Bivalvia, Polyplacophora, etc.

3. **Analyze Each Option**:
- **Gastropoda**: This is a class of Mollusca.
- **Scaphopoda**: This is also a class of Mollusca.
- **Cephalopoda**: This is another class of Mollusca.
- **Decapoda**: This is not a class of Mollusca; instead, it is an order of crustaceans within the class Malacostraca.

4. **Conclusion**: Since Decapoda is an order of crustaceans and not a class of Mollusca, the correct answer is **Decapoda**.

### Final Answer:
The option that is not a class of Mollusca is **Decapoda**.

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