The correct answer is: D. Wrought iron.
Wrought iron is the purest form of iron. It is made by heating iron ore and then hammering it into shape. This process removes impurities from the iron and makes it very strong. Wrought iron is also very ductile, which means it can be easily bent and shaped.
Steel is made by adding carbon to iron. The amount of carbon in steel determines its properties. Low-carbon steel is soft and easy to work with, while high-carbon steel is hard and strong.
Cast iron is made by melting iron and then pouring it into a mold. Cast iron is very strong, but it is also brittle and can easily crack.
Pig iron is the raw material from which steel and cast iron are made. It is made by heating iron ore in a blast furnace. Pig iron is very impure and contains a lot of carbon.
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