Shell of Mollusca is derived from

Options

A. Foot
B. Mantle
C. Ctenidia
D. Placoid

Answer

To solve the question "Shell of Mollusca is derived from," we can follow these steps:

### Step 1: Understand the Structure of Mollusca
Mollusca are a diverse group of invertebrates that typically have a soft body, which is often protected by a hard shell. The shell is an important feature of many mollusks.

**Hint:** Consider the main body parts of a mollusk and their functions.

### Step 2: Identify the Options Provided
The options given are:
1. Foot
2. Mantle
3. Tinnidia
4. Plaque

**Hint:** Think about what each of these parts does in the mollusk's anatomy.

### Step 3: Analyze Each Option
- **Foot:** This is primarily used for locomotion in mollusks and does not contribute to shell formation. Therefore, this option is incorrect.

- **Mantle:** The mantle is a significant part of the mollusk's anatomy. It is a layer of tissue that covers the visceral mass and is responsible for secreting the shell. This process is known as biomineralization. Hence, this option is correct.

- **Tinnidia:** These are gills located in the mantle cavity and are involved in respiration, not shell formation. Thus, this option is incorrect.

- **Plaque:** This term generally refers to a structure found in cartilaginous fish and is not related to mollusks. Therefore, this option is also incorrect.

### Step 4: Conclusion
Based on the analysis, the correct answer is **Mantle** (Option 2), as it is the part of the mollusk that secretes the shell.

**Final Answer:** The shell of Mollusca is derived from the **mantle**.

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