Which of the following statements BEST describes how burning fossil fuels affects the atmosphere?

A. It causes an excess of carbon dioxide and methane in the atmosphere.
B. It causes a decrease in nitrogen and phosphorus in the atmosphere.
C. It causes a decrease in carbon dioxide and methane in the atmosphere.
D. It causes an excess of nitrogen and phosphorus in the atmosphere.

A. It causes an excess of carbon dioxide and methane in the atmosphere.