In Western economies, more energy is used to operate buildings

OFFICIAL EXPLANATION

Unlike Supporter assumptions, Defender assumptions are extremely hard to prephrase because there are so many possibilities for the test makers to choose from. The correct answer in this problem is a Defender, but it is unlikely that anyone could have predicted the answer. Compare this to the previous problem, where many students were able to prephrase the correct Supporter answer. Now, focus on the final sentence of the argument, which contains a premise and conclusion: Premise: Energy savings from these efficiencies [new building technologies] save several billion dollars per year today. Conclusion: 50 to 100 years from now they will save more than $200 billion per year (calculated in current dollars). So, according to the author, the new building technologies—which are already saving billions—will continue to do the same in the future and the savings will be even greater, relatively.

Answer choice (A): This is the correct answer, and a classic Defender. If the money-saving and energy-saving technology becomes too expensive to use in the next 100 years, the savings expected will not materialize. Because this idea would clearly weaken the argument, the author assumes that it does not exist, and answer choice (A) denies that the technology will become prohibitively expensive over the next century.

Answer choice (B): Although there has been an energy usage decline since the 1973 oil crisis, the author does not assume that there will be another crisis in the next 50 to 100 years. Look at the conclusion—does there seem to be a reliance on the idea in this answer? No.

Answer choice (C): Although this answer plays with the idea mentioned in the first sentence of the stimulus—that more energy is used to operate buildings than to operate transportation—no assumption is made that buildings will become a less important consumer of energy. True, buildings have saved billions in operating in costs, but the conclusion is about future savings and not about comparing buildings to transportation.

Answer choice (D): The argument is specific about technologies saving more than $200 billion per year; the author does not assume that the total bill in the next 50 to 100 years will be lower by $200 billion.

Answer choice (E): The argument is about current technologies saving money in the future. The author does not make an assumption regarding new technologies being introduced in the future.