Reading Comprehension (RC) | Re: GMAT Prep RC: The idea that equipping homes with electrical

There is one additional question in Gmatprep for this passage:

Which of the following best describes the function of the highlighted sentence?
A. It offers an alternative interpretation of a phenomenon described in the previous sentence.
B. It provides the specific evidence on which an argument described in the previous sentence is based.
C. It shifts the focus of the argument developed earlier in the passage.
D. It introduces evidence that has not been taken into account by Vanek and Cowan.
E.