Critical Reasoning

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.

I will pick "D"
Rest all shows some or other reason why pollution control measure enacted in 1986 become effective in 1989.
If any thing "D" will result in increasing pollution level.

I am with you, i picked up D as well, but it is not the OA

OA A

vishu

OA is B.

My answer is B
I feel it is B based on process of elimination

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

Can be elimination because it clearly explains this trend.

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

Keep this option becuase it talks only about an invention but it no ways tell that it is used latest one is used by the place in question.

The other three options C,D,E clearly explains the trend and can be eliminated.

Agreed, I picked B as well.
I was contemplating C for a little, since word "revised" was a bit unclear - revised up or down? We don't know.
But in the end, B just had the most weak points in relation to the argument.

I am leaning more towards B, but I'm not sure about it