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 agent is non iodinated: \nSelect and explain. \nA. lohexol, B. Diatrizoate, C. Gadolinium, D. Visipaque', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Gadolinium', 'role': 'assistant'}]