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': 'Callus becomes thick and hard like bone within \nSelect and explain. \nA. 2 weeks, B. 4 weeks, C. 6 weeks, D. 3 months', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. 3 months', 'role': 'assistant'}]