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
Which gas is NOT responsible for green house affect - 
Select and explain. 
A. Carbon monoxide, B. Ozone, C. Nitrous oxide, D. Nitrogen
A: Carbon monoxide
Answer: A: Carbon monoxide 
Explanation: Carbon monoxide (CO) is not considered a direct greenhouse gas, mostly because it does not absorb terrestrial thermal IR energy strongly enough. Reference: Global changes of planet Eah OECD, page no:48.