The collectors like pine oil xanthates and fatty acids are used during froth-flotation process of concentration of ores to

Question

$(a)\;\text{Collect the final froth from the surface} \\(b)\;\text{Enhance the non-wettability of ore particles.} \\(c)\; \text{To get the purest form.} \\ (d)\;\text{ To remove the impurities in them.}$