ANS:A - surface coating.

The Sheardising process is used for surface coating. Sheardising is a method of metal surface treatment that involves coating the surface of metal objects with a layer of zinc to provide corrosion protection. This process is often used in industries where metal parts or components are exposed to harsh environments that can cause corrosion, such as in automotive, construction, and marine applications. During the Sheardising process, the metal objects are cleaned and then immersed in a bath of molten zinc. The zinc adheres to the surface of the metal through a metallurgical bond, forming a protective layer that helps prevent corrosion and extend the lifespan of the metal parts. Therefore, Sheardising is specifically used for surface coating and corrosion protection of metal objects, making the statement "surface coating" the correct answer.