Critical Reasoning

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.

OA , after some discussion

BTG14 wrote: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.

OA , after some discussion

The correct answer must BREAK THE LINK between the CLOSING OF THE COAL PLANT and the number of people DIAGNOSED WITH TB.
One way to weaken the conclusion is to provide an ALTERNATE CAUSE -- in this case, an alternate reason for the decline in the number of people diagnosed with TB.

Answer choice 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.
Thus, because of the new technique, there are more emphysema diagnoses and fewer TB diagnoses, offering an ALTERNATE REASON for the decline in the number of people diagnosed with TB.

The correct answer is A.

In order to solve this type of a CR question you need to come up with an alternative explanation of the change (decrease in patients diagnosed with TB) mentioned in the conclusion. The argument states that epidemiologists attributed the decrease to the closing of a coal plant. IS there an answer that could offer an alternative explanation or show that coalmine might not have been responsible for people getting sick?

Thank you all...

OA is A.

Nice explanations by experts..