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: Medicine
[{'content': 'Ove symptoms of Renal failure become evident when Renal Function Deteriorates by more than \nSelect and explain. \nA. 40-50%, B. 50-60%, C. 70-80%, D. >90%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer is C (70-80%) Ove symptoms usually develop only after renal function has deteriorated by >75 - 80% (residual renal function <20%).', 'role': 'assistant'}]