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
Which of the following is not a green house gas? 
Select and explain. 
A. CO2, B. SO2, C. N2, D. Methane
C: N2
Answer: C: N2 
Explanation: Roughly 70% of air is N2 and it is not a green house gas. A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Eah's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone.