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': 'Other than nitrogen and oxygen, which one of the following is the next most abundant gas in the dry air of lower atmosphere ? \nSelect and explain. \nA. Argon, B. Carbon dioxide, C. Helium, D. Hydrogen', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]