Correct answer is option D.

• Corex is a smelting reduction process combining a melter gasifier with a reduction shaft. The process takes lump iron ore or pellets, non-coking coal, and oxygen as main inputs.
•  The main product, the hot metal can be further treated in either EAF or BOF or can be cast and sold as pig iron.
• Midrex is an ironmaking process, developed for the production of direct reduced iron (DRI). It is a gas-based shaft furnace process is a solid state reduction process which reduces iron ore pellets or lump ore into DRI without their melting using reducing gas generally formed from natural gas.
• The reactions in the flash smelting furnaces produce copper matte iron oxides and sulphur dioxide. The reacted particles fall into a bath at the bottom of the furnace, where the iron oxides react with fluxes, such as silica and limestone, to form slag.
• The Submerged-arc furnace for phosphorus production is a particular sub-type of electric arc furnace used to produce phosphorus and other products. Submerged arc furnaces are mainly used for the production of ferroalloys.
•  A reduction reaction takes place near the tip of the electrodes to facilitate the furnace’s process.