TOEFL Reading: ETS-TOEFL阅读机经 - 5P5S3KD0Q19GB8IUL$

Why does the author include information about the "energy that humans use per year" in the discussion? A. To call into question the idea that humans can use up all the energy available in Earth's energy budget B. To provide a comparison that established how huge the amount of energy flowing into Earth's energy budget is C. To explain why there must be more than one source of energy for the Earth system D. To argue that the use of energy by humans amounts to such a small part of Earth's energy budget that it cannot have significant effects