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': 'Frequency of sound waves used for transabdominal ultrasonography is \nSelect and explain. \nA. 2.5-3.5 MHz, B. 3.5-5.0 MHz, C. 5.0-7.5 MHz, D. 7.5-10 MHz', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. 3.5-5.0 MHz', 'role': 'assistant'}]