This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals in Radiology, Subject name: Radiology
[{'content': 'Which of the following contrast agents is preferred in a patient with 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 agents of choice in patients with pre exiting renal insufficiency Low osmolar contrast agents are ionic dimers and non ionic monomers example for ionic dimer : ioxoglate example for non ionic monomer : iohexol', 'role': 'assistant'}]