[单项选择]In spite of rising concern in the Northeast and Canada, Administration spokesmen have repeatedly insisted that nothing could really be done about acid rain and the industry-produced sulfur emissions until all the scientific facts were in. Suddenly last week, however, facts came raining down, in effect making further scientific debate on what mainly causes the problem all but irrelevant. 　　What brought about the downpour was a study commissioned by Presidential Science Adviser. The spokesmen plainly called for remedial action even if some technical questions about acid rain were still unanswered. "If we take the conservative point of view that we must wait until the scientific knowledge is definitive," said the spokesman, "the accumulated deposition and damaged environment may reach the point of ’’irreversibility’’." 　　When it rains, it pours. Next came a study from the National Research Council. Its definitive conclusion: reducing emissions of sulfur dioxide from coal-burning power p
A. a heavy fall of acid rain.
B. a sudden thunderstorm.
C. a series of criticism.
D. a succession of evidence.

[单项选择]In spite of rising concern in the Northeast and Canada, Administration spokesmen have repeatedly insisted that nothing could really be done about acid rain and the industry-produced sulfur emissions until all the scientific facts were in. Suddenly last week, however, facts came raining down, in effect making further scientific debate on what mainly causes the problem all but irrelevant. 　　What brought about the downpour was a study commissioned by Presidential Science Adviser. The spokesmen plainly called for remedial action even if some technical questions about acid rain were still unanswered. "If we take the conservative point of view that we must wait until the scientific knowledge is definitive," said the spokesman, "the accumulated deposition and damaged environment may reach the point of ’’irreversibility’’." 　　When it rains, it pours. Next came a study from the National Research Council. Its definitive conclusion: reducing emissions of sulfur dioxide from coal-burning power p
A. the Administration has ignored the public anxiety about acid rain.
B. the industrial sulfur emissions need further scientific verification
C. the spokesmen have denied the presence of proofs of acid rain.
D. scientific evidence has made the cause of acid rain undebatable.