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': 'Most common cause of sub-dural haematoma - \nSelect and explain. \nA. Middle meningeal artery tear, B. Rupture of superior cerebral vein, C. Internal carotid artery tear, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: It is due to rupture of bridging veins.', 'role': 'assistant'}]