This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
[{'content': 'Xanthoproteic test is used for \nSelect and explain. \nA. Reducing sugars, B. Bile salts, C. Amino acids, D. Ketone bodies', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Xanthoproteic test: The ring systems in phenylalanine, tyrosine and tryptophan undergo nitration on treatment with concentrated nitric acid when heated (Salkowski, 1888). The end product is yellow in color which is intensified in strongly alkaline medium. This reaction causes the yellow stain in the skin by nitric acid.Ref: DM Vasudevan, 7th edition, page no: 31', 'role': 'assistant'}]