34. Why does the author begin the sentence in lines 11-12 with the phrase "If this carbon dioxide were released from Earth's rocks,.-."'
(A) To present a situation that is contrary to fact
(B) To convince readers that a certain process is harmless
(C) To describe an event that took place long ago
(D) To explain what is likely to happen in the future

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統計： A(1), B(0), C(0), D(0), E(0) #801657