Since the passage of the state’s Clean Air Act ten years ago, the leve

let us simplify the argument -

Premise -
level of industrial pollutants has fallen by 18 percent.

Two reasons are proposed for this -

One line of reasoning
Restrictions on industry placed by the Act have been effective.

Author's reasoning
Economic decline (No. of businesses fell by 10% + No. of workers employed fell by 12%) led to reduction in pollutants' levels.

We have been asked to weaken the author's reasoning.

Option A - Incorrect.
Not relevant. We are not concerned about the economic conditions in the nation, but whether economic conditions in the state led to a decline in levels of pollutants.

Option B - Incorrect.
Not relevant. This does not deny author's line of reasoning that economic decline led to decline in pollutant levels.

Option C - Correct Answer.
this suggests that reduction in the number of businesses (10%) was not responsible for the reduction in air pollution. Because the percentage of air polluting industries that closed was only 0.5%. (5 percent of 10%).
Then a 18% reduction in pollution levels could not have been caused by the closure of just 0.5% of the industries. Some other reason must account for this decline.

Option D - Incorrect.
Strengthens the argument.

Option E - Incorrect.
Kind of strengthens the argument.
lax enforcement might imply reduced compliance.
This then weakens the opposing argument that Restrictions on industry placed by the Act led to decline in levels of pollutants.

its C
A-Not helping in weaken .
B-Not giving any info whether economic condition or act was responsible for decline...
c- bingo -- tells only 5% business that ceased their operation were involved in air pollution....so most of the business that caused air pollution were still there but with improved air quality---weaken the conclusion that business decline was the reason for half of the decline in the pollution.
d-strengthen "use of word "partly"
e-not weakens

a. It is not an assumption made in the passage, rather a conclusion driven from the passage.
b. It is something out of context of the passage and doesn’t deal with the decline of industrial pollutants.
c. This could be an assumption made in the passage as the results could only be derived by making this assumption.
d. Out of context of the passage and the author didn’t compare decline of industrial pollutants among various cities.
e. Passage doesn’t approve of this statement.
Hence, c is the answer.

TWIN QUESTION: https://gmatclub.com/forum/since-the-pa ... 12928.html

Can someone please explain how option D is strengthening the argument?

Argument:
Act (factor1) -> decrease in pollutants (Supposed)
But, also Business decline (factor2) -> decrease in pollutants (also supposed)
So, factor2, and NOT factor1, is responsible for at least half of the decline in pollution. <= CONCLUSION.

Goal:
To weaken the conclusion.

Pre-thinking:
What if factor1 caused factor2? Then, indirectly, factor 1 is the actual reason.

Option D:
Several large corporations left the state during the last ten years (factor2) partly in order to avoid compliance with the Clean Air Act. (factor1)
So, factor1 is the real culprit.

Experts CrackVerbalGMAT VeritasKarishma MartyTargetTestPrep DmitryFarber egmat GMATNinja please help me out here.

Clean air act was passed 10 yrs ago.
Pollutants in the air fallen by 18 percent
During the same period the state has also suffered through economic decline - number of businesses has fallen by 10%.

Conclusion: Business decline, and not the act, is responsible for at least half of the decline in the pollution.

Because business declined by 10%, we are concluding that at least 9% of pollutants decline happened because of this, not the act.

We need to weaken this. So we need to say that the pollutant decline due to business decline may be of the order of less than 9%.

(A) During the last ten years, economic conditions in the nation as a whole have been worse than those within the state.

Irrelevant

(B) Amendments to the Clean Air Act that were enacted six years ago have substantially strengthened its restrictions on industrial air pollution.

Doesn't help us change our numbers.

(C) Of the businesses that ceased operating in the state during the last ten years, only 5 percent were engaged in air-polluting industries.

Correct. The conclusion is claiming that more than 9% of pollution decline can be attributed to business decline but the polluting businesses comprised of only 5%. The others were anyway non polluting. Then their shutting down will have no impact on pollution levels. So we can attribute less than 9% to business decline.

(D) Several large corporations left the state during the last ten years partly in order to avoid compliance with the Clean Air Act.

Were these large corporations causing pollution? We don't know. Note that the option above helps us bring this point to the fore. Even if it doesn't hit us on its own, option (C) helps us realise that we don't know whether these corporations were pollution causing. Perhaps they did not cause pollution at that time but wanted to set up some new processes but clean air act would not have allowed them to so they moved. We don't know. Point is, this option doesn't give us enough information to evaluate while option (C) is quite clear.

(E) Due to its small budget, the state office charged with enforcement of the Clean Air Act has prosecuted only two violators of the law since its passage.

If anything, it shows that clean air act may not be strictly enforced and hence may not be strictly followed.

Answer (C)

Dear VeritasKarishma

Greetings!
Kindly help to clear my doubt.
Option C states 'of the businesses that ceased operating in the state during the last ten years, only 5 percent were engaged in air-polluting industries'.
What if this 5% that was engaged in air polluting activities was the highest contributor to air pollution?
Suppose the 5% contributed to more than 9% in pollutants.
5% Industries engaged in air pollution can have a larger share in causing air pollution. So, we can attribute this change in air pollution level to economic slowdown.
Thank you.

Regards

KarishmaB ma'am,

option B says that amendments to the act were strengthened 6 years ago. Doesn't this too lead us to the conclusion that business decline was not responsible but amendments to the act were responsible for the decline in pollution?

This too weakens our conclusion. Please evaluate my reasoning.

Thanks

The conclusion is that at least 9% decline can be attributed to business decline and rest 9% or less to the act, no matter how strong or weak the act is. To weaken this we need to show why 9% may not be attributable to business or why greater than 9% may be attributable to the act. Saying that the act is stringent doesn't help us change these figures. What says that at what level of strictness will the act lead to 9% or more reduction? There is no measure of the strength of the act and its connection with the impact on pollution. So (B) is irrelevant.

Note the basis of the logic of the argument. Business saw a 10% decline. So at least half of the 18% decline in pollution (i.e. 9% or more) is because business declined by 10%. So the argument is pretty much assuming that a 10% decline in business led to a 10% decline in pollution. The rest can be attributed to the act. But if we are given that a very small fraction of the businesses used to pollute, then can we say that we can attribute 10% decline to them? No. It weakens our conclusion. Note that it doesn't prove without doubt that we can attribute very little to businesses shutting down (as you said, taking the extreme case, the 5% of the businesses could be responsible for most pollution) but it does weaken our conclusion.
gasoline

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