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: Orthopaedics
[{'content': 'Fracture shaft femur in adults usually unites by \nSelect and explain. \nA. 1 month, B. 3-4 months, C. 6-7 months, D. 1 year', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]