Which of the following has least percentage of carbon:

Wrought iron is a very pure iron where the iron content is of the order of 99.5%. It is produced by re-melting pig iron and some small amount of silicon, sulphur, or phosphorus may be present. It is tough, malleable and ductile and can easily be forged or welded. It cannot however take sudden shock. Chains, crane hooks, railway couplings and such other components may be made of this iron.

Pig iron is an intermediate product of the iron industry. Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle, and not useful directly as a material except for limited applications.

Cast iron is an alloy of iron, carbon and silicon and it is hard and brittle. Carbon content in CI may be within 1.7% to 3% and carbon may be present as free carbon or iron carbide Fe₃C. In general, the types of cast iron are (a) grey cast iron and (b) white cast iron (c) malleable cast iron etc

Steel is basically an alloy of iron and carbon in which the carbon content can be less than 1.7% and carbon is present in the form of iron carbide to impart hardness and strength. Two main categories of steel are (a) Plain carbon steel and (b) alloy steel.