求大神解决一到gre逻辑题!

求大神解决一到gre逻辑题!
Which of the following most logically completes the argument?Alivia‘s government has approved funds for an electricity-generation project based on the construction of a pipeline that will carry water from Lake Cylus,in the mountains,to the much smaller Lake Tifele,in a nearby valley.The amount of electricity generated will be insufficient by itself to justify the project’s cost,even if the price of imported oil-Alivia‘s primary source of electricity-increases sharply.Nonetheless,the pipeline project is worth its cost,because ——
（A） the price of oil,once subject to frequent sharp increases,has fallen significantly and is now fairly stable
（B） the project could restore Lake Tifele,which is currently at risk of drying up and thus of being lost as a source of recreation income for Alivia
（C） the government of Alivia is currently on excellent terms with the governments of most of the countries from which it purchases oil
（D） it would cost less to generate electricity by moving water from Lake Cylus to lake Tifele than to do so by moving water from Lake Cylus to another valley lake
（E） Alivian officials do not expect that the amount of electricity used in Alivia will increase substantially within the next ten years
这道题为什么选B?我觉得选D.B不是引入了新的内容了么?答案来自于陈虎平36套2014年01月.然后网上说选D.那到底是选什么?