The most primitive mollusc and living fossil is

Options

A. Neopilina
B. Chiton
C. Dentalium
D. Patella

Answer

To determine the most primitive mollusc and living fossil from the given options (Neopilina, Phyton, Dentalium, and Patella), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Options**: The question provides four options: Neopilina, Phyton, Dentalium, and Patella. We need to identify which of these is considered the most primitive mollusc and a living fossil.

2. **Research Neopilina**: Neopilina is known to be a genus of molluscs that exhibit characteristics of both molluscs and annelids. It has internal metameric segmentation and five pairs of nephridia, which are features that suggest a primitive evolutionary stage.

3. **Evaluate Phyton**: Phyton is not commonly recognized as a mollusc and does not have significant relevance in the context of primitive molluscs.

4. **Assess Dentalium**: Dentalium, also known as tusk shells, is a genus of marine molluscs. While it is a significant group within molluscs, it is not classified as the most primitive.

5. **Consider Patella**: Patella refers to a genus of sea snails. Although they are important marine molluscs, they do not exhibit the primitive characteristics that Neopilina does.

6. **Conclusion**: Based on the characteristics and classification, Neopilina is identified as the most primitive mollusc and a living fossil. Therefore, the correct answer is **Neopilina**.

### Final Answer:
The most primitive mollusc and living fossil is **Neopilina**.

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