The number of people diagnosed with tuberculosis in a certain city dec

Question

The number of people diagnosed with tuberculosis in a certain city decreased significantly from one year to the next. Epidemiologists attributed this decline to the closing of a coal plant on the outskirts of the city; coal fumes have long been believed to cause acute lung inflammation that can lead to the contraction of tuberculosis.

Which of the following, if true, would most seriously weaken the epidemiologists' explanation for the decrease in tuberculosis diagnoses?

A. Due to a new medical technique introduced into the city this year, many people who would have been diagnosed with tuberculosis are now correctly diagnosed with emphysema.

B. The coal plant near the city closed, at least in part, because it was found to be polluting the air with particles that are dangerous when breathed.

C. Of those diagnosed with tuberculosis last year, a large number received immediate medical treatment that halted the progression of the disease.

D. Neighboring cities that are located farther from the closed coal plant did not observe decreases in tuberculosis diagnoses this year as compared to last year.

E. Although one large coal plant closed, there are still several smaller coal plants in operation within the borders of the city.

KarishmaB · Accepted Answer

Since there was some confusion about the various options, let's discuss the question in detail.

Argument:
The number of people diagnosed with tuberculosis decreased significantly this year. 
Epidemiologists attributed this decline to the closing of a coal plant on the outskirts of the city. - we need to weaken this
Coal fumes can cause acute lung inflammation that can lead to the contraction of tuberculosis.

We need to look for some other reason for the decline in the number of tuberculosis diagnoses or something that tells us why closing of the coal plant may not be responsible for the decrease.

A. Due to a new medical technique introduced into the city this year, many people who would have been diagnosed with tuberculosis are now correctly diagnosed with emphysema.
This could certainly be a reason for the decreased number of tuberculosis diagnoses. It says that the number of tuberculosis diagnoses in the previous year was exaggerated - in this year the people who had emphysema were correctly diagnosed and were not clubbed with people who had tuberculosis. This could be a reason (other than the closing of the coal plant) for the decline in the number of tuberculosis diagnoses.

B. The coal plant near the city closed, at least in part, because it was found to be polluting the air with particles that are dangerous when breathed.
We already know this from the premises. It just tells us why it was closed. It anything, it strengthens the epidemiologists' explanation for the decrease in tuberculosis diagnoses

C. Of those diagnosed with tuberculosis last year, a large number received immediate medical treatment that halted the progression of the disease.
The treatment of those diagnosed last year is out of scope here. We are looking at the number of people who got diagnosed this year.

D. Neighboring cities that are located farther from the closed coal plant did not observe decreases in tuberculosis diagnoses this year as compared to last year.
This option also strengthens the epidemiologists' explanation for the decrease in tuberculosis diagnoses a little. It explains that cities far from the coal plant have not experienced this decrease so it is more probable now that the closing of the coal plant has resulted in the decrease of the number of tuberculosis cases.

E. Although one large coal plant closed, there are still several smaller coal plants in operation within the borders of the city.
This is out of scope too. Even if there are other harmful agents, the closing down of one major harmful agent could certainly be responsible for the decrease in the number of cases.

Answer (A)

dipzz · Answer

IMO A
A. Due to a new medical technique introduced into the city this year, many people who would have been
diagnosed with tuberculosis are now correctly diagnosed with emphysema.

This gives alternate reason for decrease in cases of TB. Due to incorrect diagnosis, the number of TB cases was high. But, now with new technique,many cases are correctly diagnosed.

Dinesh2Apr · Answer

Epidemiologists conclusion is that the closing of the coal plant is responsible for significant reduction is the no of people diagnosed with tuberculosis.

Prethinking :- we have to find some other factor that is responsible for reduction

POE :-
Option A :- Correct, this option states that closing of coal factory has not reduced the number.
Option B :- The reason for the closing of coal factory is out of scope
Option C :- This option although provide reasons for reduction in no of persons diagnosed, does not weaken the conclusion. this option can be considered as an additional factor along with the closing of factory. Hence this is not the correct answer.
Option D :- talks about cities that are farther from factory, so out of scope
Option E :- talks about other smaller plants still in operation, so out of scope.

IMO :- A

Ivan91 · Answer

Why not E ??

zthere are other coal factories in town which means that coal factories themselves are not the cause od the desease...

plumber250 · Answer

Hi Ivan,

It's actually irrelevant about the other plants. Hence others saying it is 'out of scope'.

We're looking at cause and effect between the big plant and the TB. As the amount of coal power is going down (the answer does not say there were new power plants...), then if coal is a cause of TB, then TB should go down too, even if some other plants exist.

Answer A as others have pointed out provides much more compelling evidence.

James

narenaol · Answer

A. Due to a new medical technique introduced into the city this year, many people who would have been diagnosed with tuberculosis are now correctly diagnosed with emphysema.

--This could certainly be a reason for the decreased number of tuberculosis diagnoses.Correct.

B. The coal plant near the city closed, at least in part, because it was found to be polluting the air with particles that are dangerous when breathed.

--strengthens explanation for the decrease in tuberculosis diagnoses
 
C. Of those diagnosed with tuberculosis last year, a large number received immediate medical treatment that halted the progression of the disease.

--talks about last year,not releavant

D. Neighboring cities that are located farther from the closed coal plant did not observe decreases in tuberculosis diagnoses this year as compared to last year.

--strengthens explanation for the decrease in tuberculosis diagnoses

E. Although one large coal plant closed, there are still several smaller coal plants in operation within the borders of the city.

--This is out of scope too.

MS2020 · Answer

Hi,

I have a doubt. The question states:

The number of people diagnosed with tuberculosis in a certain city decreased significantly from one year to the next.
Epidemiologists attributed this decline to the closing of a coal plant on the outskirts of the city;

- The question stem does not mention that the number of people diagnosed with tuberculosis in a certain city decreased significantly  this year 
,it only mentions  from one year to the next .

This is the reason I eliminated Options A & C, and chose E as it seemed to be within scope.

Could you please clarify?
 GMATNinja 
 VeritasKarishma 
 plumber250

Thanks!

LIBERTYRodP · Answer

TYPE: WEAKEN
DIFFICULTY: EASY

A. Due to a new medical technique introduced into the city this year, many people who would have been diagnosed with tuberculosis are now correctly diagnosed with emphysema.    ----- Correct. We are using a cause effect relationship. So this statement says that the cause for the reduction in TBC cases could actually be to this cause (the new medical diagnosis) and, therefore, no to the cause mentioned in the stimulus (closing of the coal plant).

B. The coal plant near the city closed, at least in part, because it was found to be polluting the air with particles that are dangerous when breathed.  ------ OUT OF SCOPE. The reason why the coal plant closed is unimportant.

C. Of those diagnosed with tuberculosis last year, a large number received immediate medical treatment that halted the progression of the disease.   ------- This does not explain the fluctuation from year to year.

D. Neighboring cities that are located farther from the closed coal plant did not observe decreases in tuberculosis diagnoses this year as compared to last year.  -------- Wrong way. This could actually strengthen the conclusion, because it implies that something unusual happened in this city, and that's why they are getting different results. The closing of the coal plant could be that "something unusual".

E. Although one large coal plant closed, there are still several smaller coal plants in operation within the borders of the city.  ---- This does not weaken because it does not analyze the cause-effect relationship.

KarishmaB · Answer

I understand your concern and agree that the question or option (A) should have been better worded. Unknown source questions often have this problem. Just focus on the logic and move on.

VerbalBot · Answer

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The number of people diagnosed with tuberculosis in a certain city dec

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