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 one of the following imaging techniques gives maximum radiation exposure to the patient? 
Select and explain. 
A. Chest X-ray, B. MRI, C. CT scan, D. Bone scan
C: CT scan
Answer: C: CT scan 
Explanation: Radiation exposure (in decreasing order)
CT scan > Bone scan > X-ray
MRI & USG has no radiation risk