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': 'Which one of the following is not greenhouse gas? \nSelect and explain. \nA. Carbon monoxide, B. Methane, C. Nitrous oxide, D. Water vapour', 'role': 'user'}, {'content': "Answer: A \nExplanation: Green House gases: Carbon dioxide Methane Nitrous oxide Water vapor Ozone Carbon Monoxide is not a greenhouse gas. Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 808", 'role': 'assistant'}]