Over the last few decades, public outcries against pollution have brou

Question

Over the last few decades, public outcries against pollution have brought about stricter regulations of emissions. The cities that had the most polluted air 30 years ago now have greatly improved air quality. This would not have happened without these stricter regulations.

Which one of the following can be inferred from the statements above?

Which one of the following can be inferred from the statements above?

(A) In the city with the worst air pollution today, the air quality is better than it was 30 years ago.
(B) No city has worse air pollution today than it did 30 years ago.
(C) Most of the public outcries against pollution came from people in the cities that had the most polluted
air.
(D) The most polluted cities today are not the cities that were the most polluted 30 years ago.
(E) Public criticism led to an improvement in the air quality of the cities that had the most polluted air 30 years ago.

CrackverbalGMAT · Answer

The right answer here should be  E . As always, it is important to first identify this as an inference question, which means we have to select a conclusion that MUST be true from the given statements. The GMAT looks to create confusion with such questions by  giving us answers that can be true, but can also be false . Since the correct answer cannot be false, we should look to try to prove each option as false and eliminate the ones that can be.

A  - Although it seems likely, we cannot know this for sure. We know that  on the whole , pollution has dropped. However, we  cannot say for any individual city whether it is less polluted or more , only that the average has dropped. It's possible that the worst city is actually more polluted.  OUT

B  - This is wrong for the same reason that A is wrong. If even one city has worse pollution than it did before (certainly possible) then it immediately makes this option incorrect.  OUT

C  - Again, we don't know this for sure. We know there was outcry  in general , and that the pollution got better as a result,  in general . But there's no info about where the outcry was most, or where it was at all.  OUT

D  - This too seems tempting, but we can't know for sure. It could be the case that the same cities are still the most polluted of the lot, or that they are not. We just know that the overall pollution dropped.  OUT

E  - This option works because there is NO WAY you can make it false. We know there was public criticism for sure, that it resulted in overall air quality improvement, and that the cities most polluted are now less than what they used to be.  None of this can be disputed , and this is what makes option E  CORRECT .

One thing that inference questions often reveal to us is how little we can say is 100% true, and how much we rely on assumptions. All the other options seem quite likely based on what we know about the real world, solely from the argument there is no way to say that they are true beyond doubt.

- Matoo

Doer01 · Answer

Hi Folks,
 Something has happened over the last three decades. People have been complaining about pollution and this has brought stricter regulations of emissions. 
This course of action has improved air quality of the cities that had MOST polluted AIR 30 years ago.
Conclusion: Stricter regulations have improved air quality.
Since this is an inference question, the correct choice must be true and in line with the information provided.

Not mentioned anywhere in the passage. Incorrect

We dont know that. there could be cities where regulations were not made stricter and air quality is still bad/good. Incorrect

We dont know this either. Its not mentioned in the passage where did people actually complain. Incorrect

A very keen play of modifier here. Cities that had most polluted AIR is not same as most polluted cities. Plus, we dont know whether these cities are the ones that had stricter emission regulations implemented. Incorrect

Now, this is something that Author has been trying to say in the opening sentence of the argument. Correct!

VerbalBot · Answer

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Over the last few decades, public outcries against pollution have brou

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