[求助]再论天山-4-2

annawj

看了所有前辈们的解释还是觉得有问题

天山-4-2

Twenty years ago, Balzania put in place regulations requiring operators of surface mines to pay for the reclamation of mined-out land. Since then, reclamation technology has not improved. Yet, the average reclamation cost for a surface coal mine being reclaimed today is only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines in the years immediately after the regulations took effect.
Which of the following, if true, most helps to account for the drop in reclamation costs
described?
A. Even after Balzania began requiring surface mine operators to pay reclamation
costs, coal mines in Balzania continued to be less expensive to operate than coal
mines in almost any other country.
B. In the twenty years since the regulations took effect, the use of coal as a fuel has
declined from the level it was at in the previous twenty years.
C. Mine operators have generally ceased surface mining in the mountainous areas of
Balzania because reclamation costs per ton of coal produced are particularly high
for mines in such areas.
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D. Even after Balzania began requiring surface mine operators to pay reclamation
costs, surface mines continued to produce coal at a lower total cost than
underground mines.
E. As compared to twenty years ago, a greater percentage of the coal mined in
Balzania today comes from surface mines.

目前较权威的lawyer解释是：原文要解释的是：今天表层煤矿回填费用的减低。（相比20年前）。C说的是现在回填费用高的山区不开采煤矿了，不需要回填拉。这样需要回填的都是费用低的，所以平均费用就降下来啦。故为答案。A和别的国家比，错。B讲的是煤的用途比例变化，无关，错。D和地下煤比，错。E 讲的是表层煤量的变化，无关。

但偶认为文中要求采取回填的地区只有Balzania，而c选项说停止了在Balzania的开采，此选项不涉及在其他费用低的地方开采，事实上就不存在回填费用降低的问题了，因为已经不需要回填费用了。所以c选项似乎不对。

我认为e选项正确，意思说现在开采的效率（percent）高了，(relamation technology didn't improve, but the coal mining technology can be improved.) 开采同样多的surface能开采的出来的煤数量上比20年前多，所以平均下来回填的总费用不变，但煤的吨数增多，正好可以解释为什么...only four dollars per ton of coal that the mine produced, less than half what it cost to reclaim surface mines ...