[逻辑小分队] 求解答~！Prep 08 Part I 疑问

Technologicalimprovements and reduced equipment costs have madeconverting solar energy directly into electricity far more cost-efficient inthe last decade.  However, the thresholdof economic viability for solar power (that is, the price per barrel to whichoil would have to rise in order for new solar power plants to be moreeconomical than new oil-fired power plants) is unchanged at thirty-fivedollars.

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

(A)  The cost of oil has fallen dramatically.

(C)  Technological changes have increased the efficiency of oil-firedpower plants.

这俩选项是我纠结的。分析是这样说的：

A：在推理文段中，其实油价是一个量度的标准，真正比较的是经济效益，所以本选项不能反驳结论。

C.  本选项直接谈及经济效益，可以有效的反驳结论。