Concept:Alkanals (aldehydes) are easily oxidized, while alkanones (ketones) are not easily oxidized by mild oxidizing agents.Explanation:Fehling’s solution is a mild oxidizing agent used to detect aldehydes.Alkanals reduce Fehling’s solution, producing a brick-red precipitate of copper(I) oxide, Cu2O.Alkanones do not react with Fehling’s solution under the same conditions.Therefore, Fehling’s solution can distinguish between them.Answer:D. Fehling’s solution