For logical reasoning style reading comprehension questions, first identify the question task, which in this case is to identify an assumption required by the conclusion.

Then, identify the conclusion of the argument, in this case that if appliances that are twice as energy-efficient as those currently available are produced energy consumption by home appliances will eventually be reduced to about ten percent.

Next, work through the choices looking for reasons to eliminate while considering the impact of the new information on the conclusion.

(A) If home-appliance usage did not increase with the energy efficiency, then it seems more likely that consumption would decrease, so keep Choice A as a possible assumption.
(B) The variable of expense is not discussed in the prompt, so eliminate Choice B for requiring additional information.
(C) The argument is predicated on the conditional of "if" the appliances are produced, so eliminate Choice C for having no impact on the conclusion.
(D) The variable of cost is not discussed in the prompt, so eliminate Choice D for requiring additional information.
(E) The argument is predicated on the conditional of "if" the appliances are produced, not what happens if they are not, so eliminate Choice E for having no impact on the conclusion.

Select Choice A for providing an assumption that supports the conclusion that producing energy-efficient home appliances would reduce energy consumption.