This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'The L or D form of a sugar is determined by its relation to: \nSelect and explain. \nA. Fructose, B. Glycogen, C. Glyceraldehyde, D. Glucose', 'role': 'user'}, {'content': 'Answer: C \nExplanation: An optical isomer can be named by the spatial configuration of its atoms.The D/L system does this by relating the molecule to glyceraldehyde.Glyceraldehyde is chiral itself, and its two isomers are labeled D and L', 'role': 'assistant'}]