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': 'Ultrasonography transducer contains - \nSelect and explain. \nA. Sodium Fluoride, B. Lead Zirconate, C. Caesium Fluoride, D. Barium titanate', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Lead Zirconate titanate is the most widely used piezoelectric material in the ultrasound transducers. Barium titanate was the first discovered piezoeletric material.', 'role': 'assistant'}]