Refer to the NASA article "Responding to Climate Change." Which statement best describes the author's viewpoint in the text?

A. NASA's programs are vital in helping the world's scientists learn more about climate change and its consequences

B. Throughout history, people and societies worldwide have had to learn to live with changes in climate.

C. NASA studies greenhouse gas emissions in the earth's largest cities with their Megacities Carbon Project.

D. Humans should avoid changing climate systems so ecosystems' gas levels can stabilize naturally