To manufacture steel, several steps are involved in the process. The correct sequence of these steps is (ii) - (i) - (iv) - (iii).

(i) Pig iron: The first step in manufacturing steel is the production of pig iron. Pig iron is produced by smelting iron ore in a blast furnace. Iron ore, along with coke (carbon) and limestone, is fed into the blast furnace, where it is heated to a high temperature. The iron ore is reduced to iron, and the impurities are removed, resulting in pig iron.

(ii) Blast furnace: The second step is the use of a blast furnace. The blast furnace is a large structure where the iron ore, coke, and limestone are fed from the top. Hot air is blown into the furnace from the bottom, creating a chemical reaction that produces molten iron. The impurities are removed as slag, and the molten iron is collected at the bottom of the furnace.

(iii) Shaping metal: The third step is shaping the molten iron into the desired form. This can be done through various processes such as casting, forging, or rolling. Casting involves pouring the molten iron into molds to create specific shapes. Forging involves heating the iron and shaping it using mechanical force. Rolling involves passing the molten iron through rollers to shape it into sheets or bars.

(iv) Steel making: The final step is steel making. Steel is made by adding specific amounts of carbon and other alloying elements to the molten iron. This process is known as steel making or steel refining. The carbon content is controlled to achieve the desired strength and properties of the steel. Different methods, such as the basic oxygen process or the electric arc furnace process, can be used for steel making.

In conclusion, the correct sequence of steps to manufacture steel is (ii) - (i) - (iv) - (iii). The iron ore is first smelted to produce pig iron in a blast furnace. The pig iron is then shaped into the desired form, and finally, the molten iron is refined to produce steel by adding carbon and other alloying elements.