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: Surgery
[{'content': 'A patient of 40 years male got a blow on the angle region of mandible and he is asymptomatic. The x-rays of that region shows a radiopaque line with very sharp undercut in the lower border of mandible which may be due to: \nSelect and explain. \nA. Sutural diastasis, B. Overlapping sign, C. Separation sign, D. Non union sign', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]