【求指教！】新prep一道逻辑题，完全没有看懂……

ptlove4ever

Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade.  However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.

Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?

A. The cost of oil has fallen dramatically.

B. The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.

C. Technological changes have increased the efficiency of oil-fired power plants.

D. Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.

E. When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.


答案是C
文章没有看懂，特别是括号里边的部分。
求指教！

ptlove4ever

个人的翻译：
通过技术进步以及降低设备开支，使得太阳能转化成电能技术比过去十年更加划算。但是，太阳能经济有效性的开始（也就是说，每桶油价格。。。blabla，就没读明白了）一直不变，保持在35美元

HarrisZheng

括号里面就是解释economic viability for solar power 的

也就是说，如果要让太阳能发电比石油发电更为经济，那么石油的价格必须涨到的某个价格

ptlove4ever

懂了，谢谢楼上~