Solution

1] Molisch's test : $$\rightarrow $$ it detects the presence of carbohydrate eg. Lactose, Glucose, Fructose 2] Barfoed's test: $$\rightarrow$$ It detects the presence of Monosaccharides $$RCHO + 2Cu^{2+} +2H_2O\rightarrow RCOOH+\underset{Brick\,red}{Cu_2O}\downarrow+4H^+$$ 3] Biuret's test: $$\rightarrow$$ it detects the presence of peptide bond so, Lactose - carbohydrate (Disaccharide) Glucose - Carbohydrate (Monosaccharide) Albumin - protein not carbohydrate Alanine - it has a peptide bond. Fructose - Carbohydrate. (Monosaccharide) Sucrose - Carbohydrate, Disaccharide Lactose: Molisch’s Test Glucose: Molisch’s Test and Barfoed Test Albumin: Biuret Test So, A, B, and C respectively are Lactose, Glucose, Albumin. Hence option D is correct.