This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
[{'content': 'Investigation of choice in spontaneous Sub arachnoid bleed \nSelect and explain. \nA. CT scan, B. Ventriculography, C. Ultrasound, D. Cerebral angiography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) CT scan', 'role': 'assistant'}]