This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Which of the following clinical specimen for detection of BK polyomavirus by electron microscopy? \nSelect and explain. \nA. Brain tissues, B. Urine, C. Blood, D. None of the above', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Urine (Ref: Dr D.R. Arora, 3rd/e, p. 552)* BK virus was isolated from urine of a renal transplant recipient, causes subclinical infection of children before the age of 10; virus persists for throughout life in kidneys. Reactivation may occur in last trimester of pregnancy and following immunosuppression for organ transplantation.", 'role': 'assistant'}]