Answer the following question given this paragraph: 

Because of human activities, there is more carbon dioxide in the atmosphere today than in the past hundreds of thousands of years. Burning fossil fuels and has released great quantities of carbon dioxide into the atmosphere. Cutting forests and clearing land has also increased carbon dioxide into the atmosphere because these activities reduce the number of autotrophic organisms that use up carbon dioxide in photosynthesis. In addition, clearing often involves burning, which releases carbon dioxide that was previously stored in autotrophs.


Q: Cutting forests and clearing land has also increased the amount of what in the atmosphere?

 Choices:

- oxygen

- smog

- pesticides

- carbon dioxide

A:
carbon dioxide
