16. 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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All the best!!
shinewine

I'll go with E.

I would go with D.
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SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

If the mayor exempted companies from pollution control measures it could explain the high pollution levels of 1988??

I would go with B. The invention of the spectrograph cannot contribute to rise or fall in pollution levels IMO.

As said in the passage that levels were monitered using gas spectrography. In 1989 they using the new improved instrument they found that the earlier instrument was giving inaccurate information in 1987 to 1988. But in 1989, it was found that because of bad instrument the days that were considered high pollution days were actually not high pollution days. So it explains levels in all those years.
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SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

will go with D

I convinced with D.

Yes, but there is no evidence that the new spectrometer was used. We cannot assume that the new spectrometer was used. B just states a fact that there was an invention. It does not indicate that the new invention was used.

D, to an extent explains a possibility that due to corruption the pollution levels were quoted so low. Agreed that we dont know other sources of pollution. But, D states one possibility which we cannot refute (The argument says to assume each statement is true) and it takes a step in the direction of explaining the drop in pollution levels. There are no two ways about it.

However, even after citing B, we still need to know whether the new spectrometer was used or not.

Wot say?