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': 'Signs and symptoms of a Renal Failure first appear when Renal function deteriorates by more than: \nSelect and explain. \nA. 20%, B. 40%, C. 60%, D. 80%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer is C (>60%): Signs of renal failure become apparent when renal function deteriorates by more than 60% ( residual renal function between 20-50%) while ove symptoms usually develop only after renal function has deteriorated by >75 - 80% (residual renal function <20%)', 'role': 'assistant'}]