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
Which of the following is not a ketose? 
Select and explain. 
A. Ribose, B. Erythrulose, C. Fructose, D. Ribulose
A: Ribose
Answer: A: Ribose 
Explanation: Ketoses: sugars with keto group. Ex: Dihydroxyacetone, Erythrulose, Xylulose, Ribulose, Fructose, SedoheptuloseRef: DM Vasudevan, 7th edition, page no: 70