atmospheric rise of carbon dioxide hot air from air conditioner exhaust methane gas escaping from landfills body heat generated by overpopulation
I gave my students this multiple choice question: Which of the following is believed to be one cause of global warming?

Only one answer is correct among these 4 choices:
- atmospheric rise of carbon dioxide
- hot air from air conditioner exhaust
- methane gas escaping from landfills
- body heat generated by overpopulation

Could you tell me which one is correct?

atmospheric rise of carbon dioxide