This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Surgery
[{'content': 'Commonest cause of non traumatic subarachnoid hemorrhage \nSelect and explain. \nA. Idiopathic, B. Berry aneurysm rupture, C. Hypertension, D. AV malformation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Berry aneurysm ruptureRef: Bailey 26th 320 Schwartz 10th 1730* Most common cause of SAH - TRAUMA* Most common cause of non traumatic subarachnoid hemorrhage - BERRY ANEURYSM RUPTURE', 'role': 'assistant'}]