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
All of the following investigations use non-ionizing radiation, except: 
Select and explain. 
A. MRI, B. Radiography, C. Thermography, D. Ultrasonography
B: Radiography
Answer: B: Radiography 
Explanation: Radiography is the procedure in which film is exposed as ionizing radiation passes through the patient and shows internal body structures in profile. Ultrasonography, thermography and MRI use non ionizing radiation. Ref: Essentials of Human Disease By Leonard V C roley, Pages 8-11; Grainger and Allison's Diagnostic Radiology, 4th Edition, Page 606