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 greenhouse gas? \nSelect and explain. \nA. CO2, B. SO2, C. CFC, D. Ozone', 'role': 'user'}, {'content': "Answer: B \nExplanation: Greenhouse gases are CO2 Methane CFC 12 HCFC 22 Nitrous oxide Tetrafluoromethane SO2 is not a Greenhouse gas but it causes global warming Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 794", 'role': 'assistant'}]