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
Commonest cause of non traumatic subarachnoid hemorrhage 
Select and explain. 
A. Idiopathic, B. Berry aneurysm rupture, C. Hypertension, D. AV malformation
B: Berry aneurysm rupture
Answer: B: Berry aneurysm rupture 
Explanation: 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