______ is a process of heating the concentrated ore at the temperature below its melting point in the presence of air.

The correct option is B Roasting
Roasting is a process of heating the concentrated ore at the temperature below its melting point in the presence of air.

Sulphide ores are transformed into its oxide by this process.

For example, zinc sulphide is converted to zinc oxide by heating it in the presence of oxygen.
The reaction involved is given below:

$\text{2ZnS(s)}+{\text{3O}}_2\text{(g)}\to \text{2ZnO(s)}+{\text{2SO}}_2\text{(g)}$