Drossing is a __________ operation.

ANS:C - roasting

Roasting is a process used in metallurgy to convert ores into their oxides. It involves heating the ore in the presence of air, which allows certain volatile components, such as sulfur and arsenic, to be removed as gases, leaving behind the desired metal oxide. Roasting is often a preliminary step before further processing of the ore, such as smelting or refining.