A fold of dorsal body wall which covers the visceral mass in molluscs is called as

Options

A. Operculum
B. Mantle
C. Shell
D. None of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term that describes a specific structure in molluscs, which is a fold of the dorsal body wall covering the visceral mass.

2. **Identifying Key Features of Molluscs**: Molluscs are characterized by certain features, including the presence of a mantle, a radula, and a unique nervous system structure.

3. **Defining the Mantle**: The mantle is a significant part of the molluscan anatomy. It is defined as a layer of tissue that lies between the shell and the body of the mollusc.

4. **Function of the Mantle**: The mantle serves to cover the visceral mass, which contains the internal organs. Additionally, it plays a crucial role in the formation of the shell, as it secretes materials such as calcium carbonate.

5. **Selecting the Correct Answer**: Given the options provided:
- a. upper column
- b. mantle
- c. cell
- d. none of these

The correct answer is **b. mantle**, as it is the term that accurately describes the fold of the dorsal body wall that covers the visceral mass in molluscs.

6. **Conclusion**: The answer to the question is **b. mantle**.

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