题目内容：
根据以下材料，回答题。
What problem does the authors of the new analysis raise?
A. The coal reserves are big enough.
B. All the fuel will be burnt before there is enough carbon dioxide.
C. Coal-burning could easily make up the shortfall of oil and gas reserves.
D. Oil and gas will run out so fast that Earth's doomsday will never materialize.
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