Emissions from automobiles that burn gasoline and automobiles that bur

Question

Emissions from automobiles that burn gasoline and automobiles that burn diesel fuel are threatening the quality of life on our planet, contaminating both urban air and global atmosphere. Therefore, the only effective way to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner-burning fuels, such as methanol, that create fewer emissions.

Which one of the following is an assumption on which the argument depends?

(A) Reducing the use of automobiles would not be a more effective means to reduce automobile emissions than the use of methanol.

(B) There is no fuel other than methanol that is cleaner-burning than both diesel fuel and gasoline.

(C) If given a choice of automobile fuels, automobile owners would not select gasoline over methanol.

(D) Automobile emissions constitute the most serious threat to the global environment.

(E) At any given time there is a direct correlation between the level of urban air pollution and the level of contamination present in the global atmosphere.

Bunuel · Accepted Answer

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.

ywilfred · Answer

Premise:
1) Emissions from autmobiles that burn gasoline/diesel fuel contaminate urban air and global atmosphere
2) Threathen quality of life

Conclusion:
3) ONLY effective solution is to replace diesel/gasoline with cleaner-burning fuels (methanol) that create fewer emmissions.

Which one of the following is an assumption on which the argument depends? 

(A) Reducing the use of automobiles would not be a more effective means to reduce automobile emissions than the use of methanol. 
- A. shows that only effectiv solution is to replace the type of fuel used.

(B) There is no fuel other than methanol that is cleaner-burning than both diesel fuel and gasoline. 
- Out. The use of such as in the conclusion suggests there's more than just methanol that can do the trick

(C) If given a choice of automobile fuels, automobile owners would not select gasoline over methanol. 
- not important

(D) Automobile emissions constitute the most serious threat to the global environment. 
- does not hold up conclusion

(E) At any given time there is a direct correlation between the level of urban air pollution and the level of contamination present in the global atmosphere.
- out of scope

A it is.

BussinesArtist · Answer

Everyone here is saying A mostly, but I feel A has no direct connection to the Conclusion, A totally takes over the conclusion, meanwhile D when negated weakens the conclusion and as LET says D is the least Extreme while A is the most extreme.
I am with D, but need an expert to provide solution with reasoning.

GMATNinja · Answer

The conclusion is that "the    only    effective way to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner-burning fuels, such as methanol, that create fewer emissions."

If reducing the use of automobiles is a more effective way to reduce emissions, then replacing diesel/gasoline with cleaner-burning fuels would NOT be the  only  effective way to reduce emissions. There would be at least two effective ways to reduce emissions in that case, so the conclusion would be invalidated.

As for (D), the author says that the emissions are threatening the quality of life on our planet, contaminating both urban air and global atmosphere. That doesn't mean that the emissions have to be the MOST serious threat to the global environment. Maybe the emissions are in the top 5 but not #1. The author's argument would remain the same.

So (A) is the best answer.

I hope this helps, and welcome to GMAT Club!

David nguyen · Answer

Emissions from automobiles that burn gasoline and automobiles that burn diesel fuel are threatening the quality of life on our planet, contaminating both urban air and global atmosphere. Therefore, the only effective way to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner-burning fuels, such as methanol, that create fewer emissions.

The very important strategy that I have learnt so far is spending a little bit extra time on looking for  MODIFIERS  in the conclusion.  I always evaluate whether the conclusion is: Certain or Uncertain, Extreme or Not Extreme, The only vs One of the ways, Probable vs Certain, etc.

In this case, the conclusion says replacing conventional diesel fuel and gasoline with cleaner-burning fuels is THE ONLY way. Therefore, any answer choice that eliminates the alternative plan must be correct.

Which one of the following is an assumption on which the argument depends?

This matches our thought. Hang on to this.
 
"The only effective way": Fuel is not the only possibility. There are other alternatives, such as electric vehicle, encouraging the use of public transits... (B) is out.
 
The choice is not guarantee. Furthermore, If there were a better choice than both gasoline and methanol, automobile owners would have been opted in for that choice. (C) is out.
 
Does this have to be true? "The most serious threat": Nowhere in the reasoning that the author implied this. He merely stated that Emission from Automobiles threatens the atmosphere. There could be other threats that were way more serious than Emission from Automobiles. (D) is out.
 
Irrelevant. We only care about the plan. Correlation is out of the discussion.

(A) is the only one left. (A) is our choice.

CEdward · Answer

Emissions from automobiles that burn gasoline and automobiles that burn diesel fuel are threatening the quality of life on our planet, contaminating both urban air and global atmosphere. Therefore, the  only effective way  to reduce such emissions is to replace the conventional diesel fuel and gasoline used in automobiles with cleaner-burning fuels, such as methanol, that create fewer emissions.

Which one of the following is an assumption on which the argument depends?

(A) Reducing the use of automobiles would not be a more effective means to reduce automobile emissions than the use of methanol. CORRECT
-the passage states that replacing conventional sources with cleaner-burning fuels IS THE ONLY effective way
-A) annihilates the argument by suggesting an even better alternative

(B) There is  no fuel other than methanol  that is cleaner-burning than both diesel fuel and gasoline.
-there may be other fuels that are cleaner-burning, but the argument still stands...switching is GOOD

(C) If given a  choice  of automobile fuels, automobile owners would not select gasoline over methanol.
-'consumer choice' is irrelevant

(D) Automobile emissions constitute the  most  serious threat to the global environment.
-extreme language...this can be false and the argument would still stand

(E) At  any given time  there is a direct correlation between the level of urban air pollution and the level of contamination present in the global atmosphere.
-"ANY" given time...again this doesn't have to be true and the argument isn't weakened after negation

VerbalBot · Answer

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