求助XY12-天山4-02

T-4-Q2

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?

1. 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.

2. 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.

3. 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.

4. 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.

5. As compared to twenty years ago, a greater percentage of the coal mined in Balzania today comes from surface mines.

答案是C。 不解！ 我觉得绝对不能解释上面的 drop in reclamation costs。 而E， 能做到这点，因为他说从surface mines.单位煤的产量增大了，这不就是解释了那个成本的减少吗

不知理解对否，请指教，谢谢

我觉得选B, 首先，他说reclamationt technique 没有改进，可以价格下降不是由technique造成的。所以是供需造成的.c 太绝对了.