The purification method among the ones listed that is based on the principle of "Solubility" in two different solvents is Option D, Differential Extraction.

Differential extraction, also known as liquid-liquid extraction or solvent extraction, is a technique to separate compounds based on their relative solubilities in two different immiscible liquids, usually water and an organic solvent. It exploits the fact that the compound of interest has different solubility properties in two solvents which are not miscible with each other. A solution containing the desired compound and impurities is mixed with a second solvent in which the desired compound is more soluble. The two solvents form layers due to their immiscibility, and the compound partitions into the layer where it is more soluble. By separating the layers and repeating the process if necessary, a higher degree of purification can be achieved for the target compound.

Let's quickly review why the other options do not primarily use solubility in two different solvents:

• Distillation (Option A): Distillation is a process that separates the components of a mixture based on differences in their boiling points. It does not rely on differential solubility in two solvents.


• Sublimation (Option B): Sublimation is the phase transition of a substance from the solid to the gas phase without passing through the intermediate liquid phase. This process is based on the volatility of the substance, not on its solubility in solvents.


• Column Chromatography (Option C): Column chromatography separates compounds based on their differing affinities to a stationary phase (often a solid) and a mobile phase (often a liquid). The separation is achieved by partitioning between the phases, but it does not primarily involve the solubility of the compounds in two different immiscible solvents.