This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ultrasonography, CT, and MRI, Subject name: Radiology
[{'content': 'Which of the follow ing techniques use piezoelectric crystals? \nSelect and explain. \nA. Ultrasonography, B. X-ray diffraction, C. NMR imaging, D. Xeroradiography', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e.. Ultrasonography {Ref: Sutton 6th/e p. 12: Grainger 4th/ep. 102]o Ultrasonography is based on piezoelectric effect.o MR! is based on gyeromagnetic property of proton (H+).", 'role': 'assistant'}]