ANS:B - employs two solvents

Fractional solvent extraction typically employs two solvents. In fractional solvent extraction, also known as liquid-liquid extraction or solvent extraction, the solute is transferred from one solvent phase to another solvent phase. The process involves bringing two immiscible solvents into contact with each other, with one solvent typically being more polar or hydrophilic and the other less polar or hydrophobic. By exploiting the differences in solubility of the solute in the two solvents, the desired component(s) can be selectively transferred from one phase to the other. Using two solvents allows for a more efficient separation process because it enables the creation of a concentration gradient across the interface between the two solvent phases, facilitating mass transfer of the solute from one phase to the other. Therefore, the correct completion to the statement is: Fractional solvent extraction employs two solvents.