Concept: Wrought iron is the purest commercial form of iron, containing only about 0.1% carbon.Explanation:• Pig iron contains about 3–4% carbon.• Cast iron contains about 2–4% carbon.• Iron pyrite is not iron; it is FeS2.• Wrought iron has the lowest carbon content, about 0.1% carbon, making it the purest form of iron listed.Answer: B. wrought iron