请教OG13 SC107，谢谢各位

mslancaster

107. While it costs about the same to run nuclear plants as other types of power plants, it is the fixed costs that stem from building nuclear plants that makes it more expensive for them to generate electricity.
(A) While it costs about the same to run nuclear plants as other types of power plants, it is the fixed costs that stem from building nuclear plants that makes it more expensive for them to
generate electricity.
(B) While the cost of running nuclear plants is about the same as for other types of power plants, the fixed costs that stem from building nuclear plants make the electricity they generate more expensive.
(C) Even though it costs about the same to run nuclear plants as for other types of power plants, it is the fixed costs that stem from building nuclear plants that makes the electricity they generate more expensive.
(D) It costs about the same to run nuclear plants as for other types of power plants, whereas the electricity they generate is more expensive, stemmingfrom the fixed costs of building nuclear plants.
(E) The cost of running nuclear plants is about the same as other types of power plants, but the electricity they generate is made more expensive because of the fixed costs stemming from building nuclear plants.


B选项中的for是什么意思？为什么不能删掉？谢谢！