This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuroradiology, Subject name: Radiology
[{'content': 'Which of the following lesion is hyperdense on CT? \nSelect and explain. \nA. Ependymoma, B. Medulloblastoma, C. Oligodendroglioma, D. Astrocytoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most Brain tumors are Hypodense on NCCT Hyperdense Brain tumors include Medulloblastoma, CNS Lymphoma, and Pineal Germinomas. NCCT showing a hyperdense lesion in 4th ventricle s/o Medulloblastoma.', 'role': 'assistant'}]