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
Epimer combination (s) is/are 
Select and explain. 
A. D-glucose & D-fructose, B. D-mannose & D-talose, C. D-glucose & D-mannose, D. D-glucose & D-gulose
C: D-glucose & D-mannose
Answer: C: D-glucose & D-mannose 
Explanation: When sugars are different from one another, only in configuration with regard to a single carbon atom, other than reference carbon atom, they are called epimers\Ref: DM Vasudevan, 7th edition, page no: 71