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: Radiology
[{'content': 'The best investigation to diagnose a case of acoustic neuroma is – \nSelect and explain. \nA. Gadolinium enhanced MRI, B. CT scan, C. Audiometric analysis, D. PET scan', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]