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: Medicine
The common cause of subarachnoid hemorrhage is- 
Select and explain. 
A. Arterio-venous malformation, B. Cavernous angioma, C. Aneurysm, D. Hypertension
C: Aneurysm
Answer: C: Aneurysm 
Explanation: None