This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors of Nervous System, Subject name: Medicine
[{'content': 'Most common brain tumor? \nSelect and explain. \nA. Astrocytoma, B. Oligodendroglioma, C. Ependymoma, D. Medulloblastoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) AstrocytomaRef: Harrison 19th ed. / 599-600* Most malignant brain tumor is Glioma( subtype - astrocytoma)* Most common brain tumor is metastasis to brain ( oat cell cancer/breast cancer /malignant melanoma)* Most common benign brain tumor is Meningioma* OC for brain tumor is gadolinium enhanced MRI', 'role': 'assistant'}]