santy wrote:
The number of people diagnosed as having a certain intestinal disease has dropped significantly in a rural county this year, as compared to last year. Health officials attribute this decrease entirely to improved sanitary conditions at water-treatment plants, which made for cleaner water this year and thus reduced the incidence of the disease.
Which of the following, if true, would most seriously weaken the health officials’ explanation for the lower incidence of the disease?
(A) Many new water-treatment plants have been built in the last five years in the rural county.
(B) Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease.
(C) Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers.
(D) Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease.
(E) The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago.
As per
OG, the correct ans choice is (C). But I think ans choice (B) weighs above (C).
OG rules out choice (B) simply because it says bottled water has been consumed in approximately same quantity by 2 classes of people; those who were diagnosed and those who were not.
Bottled water(pure water) can be considered as the best improvement of sanitary conditions at water-treatment plants. So this means the perfect improvement of sanitary conditions exposed to the two classes of people in roughly equal amount still drops the number of diagnosed people significantly. This clearly conveys that sanitary condition improvement is NOT a factor in this drop, which definitely contradicts the conclusion.
Choice (C) offers an alternate explaination (new technique proving old diagnoses wrong) for the reduction in diagnoses.
So why not choice (B), which directly contradicts the conclusion, is a better choice than choice (C), which gives an alternate explaination?
We are talking about a certain intestinal disease. Its name is not given and it is mentioned as "the intestinal disease" (showing that we are talking about the same disease) in options.
Number of people diagnosed with this disease has reduced significantly this year.
Officials attribute this decrease in the number of people diagnosed to improved sanitary conditions at water-treatment plants (which supposedly led to a decrease in incidence of the disease).
How do we weaken the explanation given by the health officials (that better conditions led to lower incidence which led to a decrease in number of people diagnosed)?
(A) Many new water-treatment plants have been built in the last five years in the rural county.
We are talking about improved sanitary conditions at water-treatment plants. How many plants are there, doesn't matter.
(B) Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease.
This option tells us that consumption of bottled spring water is not a differentiating factor between people who got the disease and those who did not. So it doesn't impact the reasoning given by the officials. Both had similar amount of bottled water consumption and hence would have similar amount of water treatment plant water consumption. We are looking for a differentiating factor. This is not correct.
(C) Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers.
Better diagnostic techniques is one of the reasons for fewer people diagnosed. Then decrease in incidence because of better sanitary conditions is not solely responsible for fewer diagnosed cases. Hence, it weakens the explanation given by the officials.
(D) Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease.
No of severe cases is out of scope.
(E) The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago.
Since there is no comparison given regarding the number of cases of the disease in neighbouring counties, this option doesn't help in any way. We are comparing the number of people diagnosed in this county last year with the number of people diagnosed in this county this year.
Answer (C)
Other than the fact that Option B is a strengthner, can we eliminate Option B on the grounds that the drinking habits of both the group of individuals exsisted before the change.