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': 'As absolute contraindication of MRI is: \nSelect and explain. \nA. Pacemaker, B. Prosthetic cardiac valves, C. Insulin pump, D. Cochlear implants', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pacemaker', 'role': 'assistant'}]