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': 'Ultrasonography transducer contain – \nSelect and explain. \nA. Sodium fluoride, B. Lead Zirconate, C. Caesium fluoride, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Lead zirconate titanate (PZT) is the most widely used material in the ultrasound transducers / probes replacing the firstly discovered barium titanate.', 'role': 'assistant'}]