This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Traumatic Brain Injury, Subject name: Surgery
Most common 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. is 'b' i.e., Berry aneurysm o Excluding head trauma, most common cause of subarachnoid hemorrhage is rupture of a saccular (Berry) aneurysm.