This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and Health, Subject name: Social & Preventive Medicine
[{'content': 'Gas causing global warming but is not a green house gas? \nSelect and explain. \nA. CO2, B. SO2, C. CFC, D. Ozone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) SO2Ref: www.sciencedirect.com/science/journal/00406090y Introduction to Astrobiology by C. Sivaram', 'role': 'assistant'}]