(important in need of )
-it's a short answer question-
how does energy reduce human impact on climate change?

Clean or green energy helps in releasing lesser air pollution and lesser carbon dioxide. That contributes in lowing down global warming and subsequent disasters like tsunami because of glacier melting , more unexpected climate changes like unexpected long-period storms, flood, typhoons,  etc.

Hope this would help.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project