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: Radiology
[{'content': 'Radiocontrast is contraindicated in all except – \nSelect and explain. \nA. Renal failure, B. Patient on metformin, C. Dehydration, D. Obesity', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Renal failure and dehydration are risk factors for contrast-induced nephropathy.\n\n\xa0 \xa0 \xa0 \xa0 \xa0 \xa0"Metformin causes an increased risk of developing contrast-induced nephropathy and subsequent lactic acidosis".', 'role': 'assistant'}]