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
Among the following, which one is not a major contributor to arid rains- 
Select and explain. 
A. Carbon dioxide, B. Carbon monoxide, C. Nitric oxide, D. Sulphur dioxide
B: Carbon monoxide
Answer: B: Carbon monoxide 
Explanation: Ans. is 'b' i.e., Carbon monoxide