Concept:Solubility helps separate substances by using their differing ability to dissolve in a solvent.Explanation:Solvent extraction uses solubility to separate a substance from a mixture.When a suitable solvent is added, the more soluble component dissolves into the solvent layer.The less soluble or insoluble components remain behind, allowing easy separation.This method shows the practical use of solubility in daily laboratory work.Answer:D. Solvent extraction