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: Microbiology
PML is caused by- 
Select and explain. 
A. CMV, B. Papova virus, C. HIV, D. Polio virus
B: Papova virus
Answer: B: Papova virus 
Explanation: JC virus, which is a polyomavirus belonging to Papovaviridae family, causes progressive multifocal leucoencephalopathy (PML).