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
Mean exposure of radiation from OPG is: 
Select and explain. 
A. 300 mR, B. 90 mR, C. 0.03 mR, D. 30 mR
B: 90 mR
Answer: B: 90 mR 
Explanation: Mean exposure of skin from IOPA is 800 mR.
Gonadal exposure is 1/10,000 of skin exposure i.e., 0.03 mR.
Mean exposure of radiation from OPG is 90 mR.