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
In clinical MR imaging, the patient is placed within a strong magnetic field; the strength of the magnetic field used most commonly is: 
Select and explain. 
A. 1.5 T, B. 0.15 T, C. 15 T, D. 7 T
A: 1.5 T
Answer: A: 1.5 T 
Explanation: 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).