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: Pathology
[{'content': 'Uremia occurs when total GFR is reduced by \nSelect and explain. \nA. 60%, B. 25%, C. 50%, D. 80%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]