Copper is extracted from its sulphiate are by

$(a)\;\text{Self reduction of the oxide and sulphide of copper} \\(b)\;\text{Electrolytic reduction} \\(c)\;\text{The carbon reduction process} \\ (d)\;\text{A displacement reaction}$

Copper is extracted from its sulphiate are by Self reduction of the oxide and sulphide of copper
Hence a is the correct answer.