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
Which of the following doesn't produce radiation hazard: September 2006 
Select and explain. 
A. MRI, B. Doppler USG, C. Both of the above, D. None of the above
C: Both of the above
Answer: C: Both of the above 
Explanation: Ans. C: Both of the above MRI is a noninvasive imaging technique that does not involve exposure to ionizing radiation. USG is based on piezoelectric effect and free from radiation.