In India, the steel production industry requires the import of

Answer: (c) Coking coal

Indian coal is high-ash, so steel plants import low-ash coking coal (Australia).

The idea

A blast furnace needs both heat and a substance that removes oxygen from iron ore. Coke, made by heating suitable coal without air, performs these roles and supports the furnace charge. Large coal deposits do not guarantee enough coal of the required coking quality.

Suitable coal is heated without air → Volatile matter is driven off → Strong porous coke remains → Coke burns in the blast furnace → Carbon monoxide removes oxygen from iron ore → Molten iron is produced

Why the others are wrong

(a) Saltpetre is for fertilisers and explosives.

(b) Rock phosphate is imported for fertilisers, not steel.

(d) Only coking coal is for steel.

The trap

India has huge coal reserves — but little good coking coal.

Elimination technique

The question concerns steelmaking inputs. Coking coal is the coke-making fuel; saltpetre and rock phosphate belong mainly to other industrial uses, so they cannot justify “all of the above”.

Also know

Limestone helps remove impurities as slag, while manganese is used in steelmaking. Jharia is an Indian coking-coal anchor. Iron-ore supply, thermal-coal supply and coking-coal supply are separate constraints; an integrated steel plant needs all of its inputs to match.