Emissions from automobiles that burn gasoline and automobiles that bur

OFFICIAL EXPLANATION

The last sentence contains the conclusion of the argument, which is conditional (note the use of the necessary condition indicator “only”): ERE = Effectively reduce emissions, Replace = Replace the conventional diesel fuel and gasoline used in automobiles with cleaner-burning fuels, such as methanol, that create fewer emissions. ERE Replace. According to the author, to effectively reduce emissions, conventional fuels must be replaced. Based on our discussion, since the stimulus does not present any conditional chains, you should look for an answer that protects the necessary condition. Answer choice (A) is a Defender that does just that, eliminating an idea that would undermine the relationship.

Answer choice (A): This is the correct answer. Consider the author’s position that the only effective way to reduce emissions is fuel replacement. Wouldn’t it be more effective to simply stop using cars altogether? Of course this is true, but this would undermine the conditional nature of the conclusion and so the author assumes that this possibility cannot occur. If this answer is troubling you, use the Assumption Negation Technique and ask yourself if the following statement would undermine the argument: Reducing the use of automobiles would be a more effective means to reduce automobile emissions than the use of methanol. This answer clearly shows that there are other, more effective ways of reducing missions and therefore the answer attacks the argument. This must be the correct answer.

Answer choice (B): The author is not committed to methanol because the stimulus clearly references “fuels such as methanol.” Accordingly, this answer is not an assumption of the argument.

Answer choice (C): The choices automobile owners would make are not part of the argument made by the author. The author simply states that the only effective way to achieve reduced emissions is fuel replacement. No assumption is made about whether automobile owners would follow that way. The problem with the answer can be highlighted by this example: An argument is made that the best way to achieve long-lasting fame is to commit suicide. Does the author assume that people will or will not choose that path? No, because the best way does not involve an assumption about how people will actually act.

Answer choice (D): This answer falls under the second of the three quirks discussed in the previous section. The author clearly believes that automobile emissions are a serious threat to the environment, but this does not mean that the author has assumed they are the most serious threat. Negate the answer and ask yourself, “What would the author say to the negation?” The author would reply that he or she never indicated that emissions were the most serious threat, so it is fine that they are not.

Answer choice (E): We know that both urban air and the global atmosphere are contaminated by cars, but the author does not indicate that there is a direct correlation between the two. This answer, when negated, has no effect on the argument (and must therefore be incorrect). In an Assumption question, there can be only one answer that will hurt the argument when negated. If you negate the answers and think that two or more hurt the argument, you have made a mistake.