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 Aldosugar? 
Select and explain. 
A. Fructose, B. Erythrulose, C. Glucose, D. None
C: Glucose
Answer: C: Glucose 
Explanation: Repeated question