Which of the following molluscs lacks radula?

Options

A. Pila
B. Pinctada
C. Limax
D. Doris

Answer

To determine which mollusc lacks a radula, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understand the Radula**:
- The radula is a specialized feeding organ found in most molluscs. It is a tongue-like structure covered with tiny teeth, used for scraping food off surfaces.

2. **Analyze the Options**:
- **Option A: Pila**: Pila is a genus of freshwater snails that possess a radula. Therefore, it does not fit our criteria.
- **Option B: Pinctada**: Pinctada is a genus of pearl oysters. These molluscs do not have a radula, as they feed by filtering plankton from the water.
- **Option C: Lamex**: Lamex is a genus of marine snails that also have a radula. Thus, it does not meet the requirement.
- **Option D: Doris**: Doris refers to a genus of sea slugs (nudibranchs) that do have a radula, so it is not the correct answer.

3. **Conclusion**:
- After analyzing all the options, we find that **Option B: Pinctada** is the only mollusc that lacks a radula.

### Final Answer:
- The mollusc that lacks a radula is **Option B: Pinctada**.