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: Forensic Medicine
[{'content': 'Provisional callus forms in fracture of bone by : \nSelect and explain. \nA. 3 days, B. 7 days, C. 14 days, D. 30 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. 7 days', 'role': 'assistant'}]