本贴相关题目 GMATPrep-2008E1-CR-107 | TN-12-CR-2 (TVAK)

00:00:00

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?

AEven 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.
BIn 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.
CMine 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.
DEven 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.
EAs compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

正确答案: C

求助，GWD-TN-12,T-4-Q2

[复制链接]

sasha_wen

楼主

发表于 2012-6-13 14:06:47 | 显示全部楼层

讲讲我的理解：
Yet后是关键：现在surface coal/coal的the average reclamation cost 下降为过去的一半，问原因？
Yet前说明了coal的分母不变因为技术没有变，地方还是Balzania这个地方，唯一能变的就只有分子上的surface coal变少才能使得整个分式减少，也就是C，仅供参考！