This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
[{'content': 'Progressive multifocal leukoencephaloPathy is caused- \nSelect and explain. \nA. Epstein-barr virus, B. Varicella-zoster virus, C. Cytomegalo Virus, D. JC Papovavirus', 'role': 'user'}, {'content': "Answer: D \nExplanation: Harrison's principles of internal medicine. *In PML oligodendrocytes have enlarged densely staining nuclei that contain viral inclusions formed by crystallinearrays of JC virus paicles.", 'role': 'assistant'}]