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': 'Which of the following is not a ketose? \nSelect and explain. \nA. Ribose, B. Erythrulose, C. Fructose, D. Ribulose', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ketoses: sugars with keto group. Ex: Dihydroxyacetone, Erythrulose, Xylulose, Ribulose, Fructose, SedoheptuloseRef: DM Vasudevan, 7th edition, page no: 70', 'role': 'assistant'}]