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
[{'content': 'Mean exposure of radiation from OPG is: \nSelect and explain. \nA. 300 mR, B. 90 mR, C. 0.03 mR, D. 30 mR', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mean exposure of skin from IOPA is 800 mR.\nGonadal exposure is 1/10,000 of skin exposure i.e., 0.03 mR.\nMean exposure of radiation from OPG is 90 mR.', 'role': 'assistant'}]