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: Social & Preventive Medicine
[{'content': 'Glycosylated haemoglobin reflects the mean blood glucose level of previous \nSelect and explain. \nA. 15 days, B. 1 month, C. 3 months, D. 6 months', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]