The ore particles should not be wetted by water.
Ore contains rocky impurities which are needed to be separated before processing. This process is called concentration of ore. The principle of froth flotation process is that sulphide ores are preferentially wetted by the pine oil, whereas the gangue particles are wetted by the water. In this process, a suspension of a powdered ore is made with water. In this process, a suspension of a powdered ore is made with water. Collectors like pine oil, fatty acids and xanthates are added to it. Froth stabilizers like cresols, aniline stabilize the froth. The minerals particles become wet by oils while gangue particles by water. The mixture is agitated with the help of mechanical stirrer by passing blast of air. The froth is formed which is lighter and skimmed off. The froth is dried for recovery of the ore particles.
Hence b is the correct answer.