This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glycogen, Subject name: Biochemistry
[{'content': 'During lack of food in diet , how many hours are needed for depletion of glycogen: \nSelect and explain. \nA. 9, B. 18, C. 24, D. 48', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans : option b -18 hrs (Best ans : 12-18 hrs) Glycogen reserves can be used for 12-18 hours.', 'role': 'assistant'}]