单选题
The author is primarily concentrated on ______.
A、
explaining the effects that the burning of fossil fuels might have on climate
B、
illustrating the effects of CO
2
on atmospheric radiation
C、
discussing effects that changes in the CO
2
level in the atmosphere might have on climate.
D、
challenging hypotheses about the effects of water vapor and CO
2
on climate
【正确答案】
C
【答案解析】
作者主要讨论大气中CO
2
含量对气候造成的影响。作者在第二段和第三段专门讨论这一问题。A不能选，因为作者只是轻描淡写地讨论这一问题。
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