an increase in undersea volcanic activity a decrease in the distance between Earth and the Sun an increase in certain gases released during the use of fossil fuels a decrease in the amount of water on Earth due to overconsumption
I gave my students this multiple choice question: Scientists have observed an increase in global temperatures over the past 100 years. Which phenomena do scientists believe contributes to the increase in temperatures?

Only one answer is correct among these 4 choices:
- an increase in undersea volcanic activity
- a decrease in the distance between Earth and the Sun
- an increase in certain gases released during the use of fossil fuels
- a decrease in the amount of water on Earth due to overconsumption

Could you tell me which one is correct?

an increase in certain gases released during the use of fossil fuels