( c) ____iron is the purest form of iron.

Explanation

**Step-by-Step Text Solution:**

1. **Identify the Question**: The question asks for the purest form of iron.

2. **Recall the Types of Iron**: There are different forms of iron, including cast iron, wrought iron, and pig iron.

3. **Determine the Purest Form**: Among these, wrought iron is known to be the purest form of iron.

4. **Explain Why Wrought Iron is Pure**: Wrought iron contains very low carbon content, typically less than 0.08%. This low carbon content contributes to its purity.

5. **List the Properties of Wrought Iron**:
- **Toughness**: Wrought iron is tough, meaning it can withstand stress without breaking.
- **Malleability**: It can be easily shaped and drawn into thin sheets.
- **Ductility**: Wrought iron can be stretched into thin wires.

6. **Conclude**: Therefore, the answer to the question is "Wrought Iron."

**Final Answer**: Wrought iron is the purest form of iron.

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