To protect the environment, paper towels in public restrooms should be

Official Explanation

STEP 1: IDENTIFY THE QUESTION TYPE

The question stem, in addition to asking for a necessary assumption, indicates that a proposal has been made.

STEP 2: UNTANGLE THE STIMULUS

The proposal is a ban on paper towels, which would be replaced by hot-air dryers; the purpose of this ban is to reduce environmental impact. The evidence used to support this proposal is that the manufacture of paper towels uses natural resources and causes emissions.

STEP 3: PREDICT THE ANSWER

To recommend the proposal, the author must assume that the environmental benefits of hot-air dryers outweigh any disadvantages. A good prediction would be that there’s nothing about hot-air dryers that would make them worse for the environment than paper towels.

STEP 4: EVALUATE THE CHOICES

(B) matches this prediction and is thus correct; since one of the stated goals of the plan is to protect the environment and this will be achieved, in part, by cutting down fewer trees, the author must be assuming that hot-air dryers use fewer natural resources than do paper towels. If increased use of hot-air dryers would cause, for example, the mining of metals for their manufacture or of coal or uranium to produce electricity, then their environmental impact might not be less than that of paper towels, and the argument would fall apart.

(A) is irrelevant; the fact that costs won’t increase might be an additional benefit of the proposal, but since the argument is strictly about environmental impact, the author isn’t assuming anything about the cost of the change.

(C) is incorrect because it’s not necessary for dryers to be the only alternative to towels for them to be the better alternative.

(D) is wrong because effectiveness is irrelevant to an argument that is based on environmental concerns.

(E) may be tempting because it might seem that the proposal won’t be effective if people aren’t willing to implement it. However, the proposal is that paper towels should be banned; even if the ban isn’t enacted, the author could still think it’s a good idea.

Answer: B