This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intracranial Space Occupying Lesion, Subject name: Medicine
[{'content': 'Which brain tumor has the worst prognosis in children? \nSelect and explain. \nA. Cerebellar astrocytoma, B. Brainstem glioma, C. Craniopharyngioma, D. Pineal body tumor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Brainstem glioma Aggressive and dangerous cancer Has worst prognosis. Without treatment life expectancy is typically few months from the time of diagnosis.', 'role': 'assistant'}]