decreasing the amount of fresh water increasing the number of animal species decreasing the average yearly temperatures increasing carbon dioxide levels in the atmosphere
I gave my students this multiple choice question: The need for farmland in Brazil has led to the cutting of the rain forests in the Amazon. Cutting trees in the Amazon rain forest might have a global effect by

Only one answer is correct among these 4 choices:
- decreasing the amount of fresh water
- increasing the number of animal species
- decreasing the average yearly temperatures
- increasing carbon dioxide levels in the atmosphere

Could you tell me which one is correct?

increasing carbon dioxide levels in the atmosphere