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': 'In clinical MR imaging, the patient is placed within a strong magnetic field; the strength of the magnetic field used most commonly is: \nSelect and explain. \nA. 1.5 T, B. 0.15 T, C. 15 T, D. 7 T', 'role': 'user'}, {'content': "Answer: A \nExplanation: In clinical MR imaging, the patient is placed within a strong magnetic field. The field strengths range from 0.1 to 7 T, with 1.5 T being the most common (1.5 T is about 30,000 times the strength of the earth's magnetic field).", 'role': 'assistant'}]