Option 1 -> Alloying is the process of mixing two or more metals to form an alloy with improved properties, not a coating method.
Option 2 -> Galvanisation is the process of applying a protective zinc coating to steel or iron to prevent rusting through sacrificial protection.
Option 3 -> Anodising is an electrolytic process that increases the oxide layer thickness, primarily used for aluminum, not zinc coating.
Option 4 -> Greasing involves applying grease or oil as a temporary rust barrier, not a zinc coating.
Hence, Option 2: Galvanisation -> This process involves coating iron or steel with zinc, which acts as a sacrificial anode and protects the underlying metal from corrosion even if the coating gets scratched -> correct