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: Medicine
[{'content': 'Regarding Progressive multifocal leucoence- phalopathy, all are true, except -a) Caused by JC virusb) Diffuse cortical matter involvementc) Disease of white matterd) Disease of grey matter \nSelect and explain. \nA. a, B. bc, C. ad, D. ac', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]