Which of the following factors is of no significance for roasting sulphide ores to the oxides and not  subjecting the sulphide ores to carbon reduction directly?

Metal sulphides are less stable than the corresponding oxides. Because there is no significance for roasting sulphide ores to the oxides and not subjecting the sulphide ores to carbon reduction directly.

Because metal sulphides are more stable than metal oxides, it is challenging to separate metal from its sulphide. As a result, metal sulphides are first transformed into oxides before being removed.