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: Social & Preventive Medicine
[{'content': 'The maximum permissible level of occupational exposure to radiation is...per year - \nSelect and explain. \nA. 5 rad, B. 2 rad., C. 10 rad, D. 50 rad', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 5 Rad The amount of radiation received from outer space and background radiation has been estimated to be 0.1 rad a year. Apparently, this does not at present constitute a hazard. The additional permissible dose from man made sources should not exceed 5 rad a year.", 'role': 'assistant'}]