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

The purest form of iron that contains only about 0.1% carbon is called "wrought iron." Wrought iron is produced by melting iron ore in a furnace and then purifying it with iron oxide. The impurities are removed through hammering, rolling, and squeezing the hot iron into shape. Wrought iron is relatively soft and malleable, making it easy to work with for blacksmiths and metalworkers. Pig iron is an intermediate product of iron processing that contains high amounts of carbon and other impurities, and it is not suitable for use in its raw form. Cast iron is another type of iron that is produced by melting pig iron with scrap iron and adding alloys to create a stronger, more brittle product. Iron pyrite is a mineral that contains iron and sulfur but is not used for industrial purposes because it is not a suitable source of iron. Therefore, the option that refers to the purest form of iron which contains only about 0.1% carbon is "wrought iron."