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': 'Which of the following is not done in a case of brain tumour? \nSelect and explain. \nA. CT scan, B. MRI, C. X-ray skull, D. Lumbar puncture', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Lumbar puncture', 'role': 'assistant'}]