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': 'Which of the following contrast agents is preferred in a patient with a decreased renal function to avoid contrast nephropathy – \nSelect and explain. \nA. Acetylcystine, B. Fenoldapam, C. Mannitol, D. Low osmolar contrast', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Low osmolar contrast agents are the contrast agents of choice in patients with pre-existing renal insufficiency.\nAcetylcysteine and fenoldopam may also be used to reduce contrast-induced nephropathy but these are not contrast agents. Further, these drugs have limited value for their use for this indication', 'role': 'assistant'}]