题目选项分析

Delta products, Inc., has recently switched at least partly from older technologies using fossil fuels to new technologies powered by electricity. The question has been raised whether it can be concluded that for a given level of output, Delta's operation now causes less fossil fuel to be consumed than it did formerly. The answer, clearly, is yes, since the amount of fossil fuel used to generate the electricity needed to power the new technologies is less than the amount needed to power the older technologies, provided that the level of output is held constant.

In the argument given, the two boldface portions play which of the following roles?

【选项】Each provides evidence that calls the conclusion of the argument into question.