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.
(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.

The correct answer is letter "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.

Explanation:

It is imperative to understand what reclamation costs are. Once some land has been mined out, cultivation needs to be put back to some use. The work is costly and it is important for operators to pay the Government for reclamation. What would make the cost of reclamation be decreased? Where technology gets better and reclaiming everywhere costs less or when high-cost areas of reclamation are not exploited. The last leads us to option letter "C". It states that mining has stopped in an especially high-cost area of reclamation. This will reduce the average cost of reclamation even if in other places may still have the same cost.