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': 'Plasma urea / creatinine ratio of 20:1 may be seen in - \nSelect and explain. \nA. Rhabdomyolysis, B. Ureteric calculi, C. Pre-renal failure, D. Chronic glomerulonephritis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]