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# In 1986, the city of Los Diablos had 20 days on which air

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In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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12 May 2009, 23:07
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In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.

Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
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In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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26 May 2010, 05:06
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In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
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In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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28 Apr 2013, 14:43
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In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.

Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.

(B) In December of 1988, a new and far more accurate gas spectrometer was invented.

(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.

(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.

(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
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Re: In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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14 Mar 2013, 07:30
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Expert's post
TheNona wrote:
still not quite convinced with B

Hi TheNona,

In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.

Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.

The question asks us to find an answer choice that is LEAST helpful in explaining the pollution levels between 1986 and 1989. (B) may explain why the smog alerts decreased in 1989, but it will not explain the rise in pollution level in 1987 or 1988.

(D) on the other hand helps to explain the levels, because the Mayor "was found" to have accepted donations and exempted industries from pollution control measures. In 1988 it was found, so it is possible that he could have been taking donations in the past also; it could explain the pollution levels in 1987 and 1988. Thus, (D) explains.

Hope this helps,

Vercules
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Re: City of Los Diablos [#permalink]

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26 May 2010, 20:55
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I vouch for B, a new gas spectrometer might have been invented in 1988, but how can we assume it served any purpose or was actually used.

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Re: City of Los Diablos [#permalink]

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26 May 2010, 22:01
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The answer is B. The reason it is the answer is because it says the new system was more accurate. Being more accurate doesn't mean that the old results are not true, it only means that they are now more certain about the levels. It does the least to tells us that that what is in the passage is true, because with B we're not certain whether the new gas spectrometer helped or made worse the evidence in the passage.

E helps because it tells us why in 1989 we started to see such a drastic drop.

D helps because it would give a good reason why the drop in incidences began.

I hope this helps.

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Re: City of Los Diablos [#permalink]

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01 Jun 2010, 12:46
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its B.

its not D because D says

In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.

Now how does one know that the pollution was because of industries and not because of say a large amount of cars on the road.
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Re: Los Diablos [#permalink]

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29 Jul 2010, 09:17
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ImJun wrote:
dont look too much into it, it's D trust me

A lot of people vote for D, I am as well. Source is 1000 series of CR questions.
This is badly constructed CR question, because a lot of people stuck on B/D answer choice. Here is a lot to assume either in B or D.

Here is the comment from a canadian istructor who scored 800.

"Who cares?
This is a garbage 1000cr question. You may as well have some random person design a question, and then feel bad because you can't choose between two answers. Practicing on these questions can HURT you more than it can help you.
rce be
People think more questions, more practice, better off. But if the kind of questions you are working on the are badly designed then a reason for why a right answer is right or why a wrong answer is wrong may not even be applicable on real GMAT questions. You might take away learnings that are bad information on the real test!"
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Re: In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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15 May 2013, 00:50
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Argument:
In los Diablos smog alerts happens when air pollution reached unhealthful amounts.
Fact1: 1986- smog alerts on 20 days
Fact2: early 1987- new air pollution control measures were enacted.
Fact3: 1987-smog alerts on 31 days
Fact4: 1988- smog alerts on 39 days
Fact5: 1989- smog alerts on 16 days
Fact6: The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.

Pre thinking
According to fact the main air pollutants are ozone and carbon monoxide and both are monitored using gas spectrography since 1986 so measuring technique can’t be cause of pollution change unless some changes happens in gas spectrography.
Pollution controls were enacted in early 1987 and pollution actually rose after that till 1988 and then came down in 1989.Looks like it took some time for the effects of measures taken in 1987 to start controlling pollution.

Analysis of answer choices:
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
INCORRECT: This helps in understanding why it took time for pollution to go down by 1989.

(B) In December of 1988, a new and far more accurate gas spectrometer was invented.
INCORRECT: This can help in understanding the reading difference in 1989 if we assume that the gas spectrometers earlier were giving higher readings than the real readings. Also we have to assume that control measures were not having much effect and thus pollution increased from 1986 to 1988.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered un healthful.
INCORRECT: This can helps us in understanding why pollution alerts went down in 1989 if we assume that the level for un healthful was raised. Also we have to assume that control measures were not having much effect and thus pollution increased from 1986 to 1988.

(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
CORRECT: this means that lesser industries are using air pollution control measures and hence air pollution should go up. However its went down in 1989 and it can’t be explained from this answer choice.

(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
INCORRECT: This helps in understanding why it took time for pollution to go down by 1989.

So D in my opinion as well . I believe official answer is incorrect.
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Re: Los Diablos [#permalink]

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14 May 2009, 09:46
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I recall this question and

The OA is B apparently, because even though the gas spectometer was invented, it doesn't mean it was used.

But I'm still sticking with D!

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Re: Los Diablos [#permalink]

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14 May 2009, 18:04
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Anyone else ?

There's one more thing that makes D the best answer: "in 1988" --> indefinite time, so I can assume that it happened at the early 1988, affecting the whole year 1988 and 1989, but why the 2 year had 2 different outcome ?

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Re: City of Los Diablos [#permalink]

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01 Jun 2010, 08:18
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Regarding D,

Doesn't it go against the given information? In '89, the smog # went down. However, if the mayor exempted companies from pollution control, there would be MORE pollution, and hence MORE smog #.

Therefore, it doesn't help in explaining why the number went down.

Why is this thinking wrong?

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Re: In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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28 Apr 2013, 14:55
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In 1986 20 days .
In early 1987, new air pollution control measures were enacted, 31 days
In 1988 39 days.
In 1989 16 days.

Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
Put into effect at the end of 1988, so the result will be seen in 1989. That's what happens (only 16 in 89), so it's a good explanation
(B) In December of 1988, a new and far more accurate gas spectrometer was invented.
CORRECT
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
Review of the scale , raising or lowering the levels (we do not know). Take the case of higher levels => less days of high pollution. It could explain the drop in 89.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures
So in the years prior to 88 the high levels were caused by those industries. In 89 those industries will not cause high pollution=> drop in 89. Good explanation
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
So the pollution will remain in the air for 2 years minimum. We'll se the result of the 87's mesures in 89(2 years later). That's what happens, so is a good explanation
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Re: In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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24 May 2013, 07:11
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BlueRobin wrote:
In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.

My initial pick was D too. But I guess after reading it the second time , I see why B makes sense.

Quote:
(B) In December of 1988 a new and far more accurate gas spectrometer was invented..

As other people have pointed out , it only says spectrometer was invented . No mention of it being used to monitor the levels.

Quote:
(D) In 1988 the mayor of Los Diablos was found to have acceptedlarge campaign donations from local industries and to have exempted those same industries from air pollution control measures. .

No doubt , the pollution increases , if mayor exempts those industries from air pollution measures. So accepting donations to exempt those industries , meant increase in air pollution. If we focus on the bold part above in D , it says in 1988 , the mayor was found to have accepted. It doesn't say that mayor ACCEPTED in 1988 and EXEMPTED the industries IN 1988. He was FOUND to have accepted in 1988. He might have accepted the donations before 1988 or in the middle of 1998 or end of 1988.They just found that thing in 1988. The exemption might have happened in 1987. Or if they found out by the end of 1988 , then exemption might have happened till they found out , in 1988. This kinda explains why the pollution increased till 1988. And mebbe once they found out in 1988 , what mayor had done , they might have reverted the exemptions , which is why in 1989 pollution went down . I know it is bit of a stretch to make these assumptions , but when we are to choose between B and D (In B - where you make an assumption that invented meant used + cant justify yet as to why did new and accurate instruments show lower pollution levels) , the assumptions what we made in D seems safer.

HTH
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Re: Los Diablos [#permalink]

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01 Mar 2014, 11:00
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I recall this question and

The OA is B apparently, because even though the gas spectometer was invented, it doesn't mean it was used.

But I'm still sticking with D!

B is right

Firstly, Argument is asking about variation in pollution level from 86 to 89
and What measure do we have in argument - number of occurrences/ frequency of alert days on which air pollution reached unhealthful amounts and a smog alert was put into effect. (highlighted part is in the first line of arg.)

Secondly, What's wrong with D - if some industries are getting exemption "from air pollution control measures."
Then, surely frequency will be affected.

B is right just because of what 'bigfernhead' has mentioned about B.
Hope it helps !
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Re: In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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05 Mar 2014, 02:46
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B, it's the right answer. B said that a new gas spectrometer was invented, but we dont know if it was used!!!

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In 1986, the city of Los Diablos had 20 days on which air [#permalink]

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11 Nov 2016, 15:36
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For me, B is correct. My analysis is below...

Structure
Contrasting Fact 1:
In 1986, City LD had 20 days on which air pollution reached unhealthful amounts --> Smog alert into effect.
In early 1987, new air pollution control measures were enacted, but[/highlig[highlight]ht] LD had smog alerts on 31 days that year and on 39 days in 1988.

Contrasting Fact 2:
In 1989, however, the number of smog alerts in LD dropped to sixteen.

LD's main air pollutants: O3 & CO,
Since 1986 the levels of both have been monitored by gas spectrography.

Pre-thinking
We have to find the option that explains the least the contrasting facts. So we can star by pre-thinking some explanations of both contrasting facts:
What if levels of both pollutants remain in the environment for at least two years?
What if pollutants' limit levels were drop significantly in 1987 when the new control measures were enacted?
What if gas spectrography device was not correctly caliber?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988. Correct
Help to explain Both contrasting points. this option would justify the rise in the number of alerts in the city for both 1987 and 1987; and the drop of alerts in 1989.

(B) In December of 1988, a new and far more accurate gas spectrometer was invented. Incorrect, so correct choice!
This option is OFS. The invention of a more accurate gas spectrometer doesn't mean that LD city used them to measure pollution.

(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful. Correct!
Aligned with pre-thinking.. in the revision they probably increase the pollution limit, so this fact explains a drop in the number of alerts.

(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures. Correct
If he accepted money in exchange for an exemption of the execution of measures, those local industries, knowing that were not going to be punished, were deliberatly contaminating the environment, explaining the high number of alerts during 1987 and 1988. Then, a drop on alters in 1989 happened after the mayor was found to receive bribes.

(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area. Correct
Aligned with pre-thinking.

Hope the analysis helps!

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Re: Los Diablos [#permalink]

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12 May 2009, 23:25
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D

if D were true then why is there a decrease in pollutants in 1989, there should have been an increase

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Re: Los Diablos [#permalink]

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13 May 2009, 03:26
bigtreezl wrote:
D

if D were true then why is there a decrease in pollutants in 1989, there should have been an increase

Yes, but it's not OA

I wanna check more posts before deciding whether the OA is wrong..

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Re: Los Diablos [#permalink]

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13 May 2009, 07:30
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Minheequang wrote:
One more doubt about OA

In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?

(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.

A) Explains why number reduced on 1988
B) This does not. If more accurate then the numbers should have increased.
C) Explains. Now new threshould is there, which maybe greater than the previous one.
D) Explains. Since companies exempted from air pollution measures, hence the decrease.
E) Since min 2 years required to break down the pollutants, hence the effects seen after 2 years..

IMO B

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Re: Los Diablos   [#permalink] 13 May 2009, 07:30

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