This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
[{'content': 'Which of the following is hypointense (dark) on T2-weighted MRI? \nSelect and explain. \nA. CSF, B. Fat, C. Edema, D. Hard calcification', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .', 'role': 'assistant'}]