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: Surgery
[{'content': 'Acute onset of anuria in elderly men \nSelect and explain. \nA. Bilateral infarction of kidneys, B. Obstructive urinary disease, C. Acute tubular necrosis, D. Acute cortical necrosis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]