The purest form of iron which contains only about 0.1% carbon is

Correct answer: wrought iron.

Explanation: Wrought iron is the purest commercial form of iron, typically containing about 0.02–0.08% carbon (≈0.1% at most). This very low carbon content makes it tough and malleable.

• Pig iron – High carbon (about 3–4.5%); very brittle.
• Cast iron – Also high carbon (about 2–4%); hard but brittle.
• Iron pyrite – FeS₂ (a mineral, “fool’s gold”), not a form of metallic iron.