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: ENT
[{'content': 'Acoustic neuroma of 1 cm diameter, the investigation of choice - \nSelect and explain. \nA. CT Scan, B. MRI Scan, C. Plain X-ray skull, D. Air encephalography', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]