A certain laboratory is studying the incidence of fatal liver damage

The feasible explanation for the statistics provided in the scenario is option (D) - Only a small portion of the entire group of rats studied was exposed to environmental sulfur dioxide.

This explanation accounts for the fact that 65% of rats exposed to low levels of sulfur dioxide died of liver disorder, while 90% of rats who died of liver disorder were not exposed to any environmental toxins. If only a small portion of the rats were exposed to sulfur dioxide, it is reasonable to assume that the majority of the rats who died of liver disorder were not exposed to toxins since most of the rats studied were not exposed to toxins. This explanation suggests that there could be other causes of fatal liver disease in rats beyond environmental toxins.

KAPLAN OFFICIAL EXPLANATION

Here's another study to ponder, and the stem alerts us to the fact that we need to find a plausible explanation for the statistics cited. That alone suggests that the stats are puzzling, or at least a bit unusual, which is reinforced by the contrast Keyword however in the final sentence. So what's going on in this one? We have a significant number of rats dying of liver disorder after being exposed to sulfur dioxide, but most of the rats who died of liver disorder were not exposed to any environmental toxins. This is not unlike what we've seen previously: a situation in which what seems like the same groups are actually not. Specifically, you should have realized immediately that the 65% and the 90% figures refer to two different groups, and thus that there is no discrepancy in the statistics. The 65% figure represents all rats exposed to sulfur dioxide; 90% represents the percentage of all rats that died of liver disorder. (D) points this out. If only a small number of rats were exposed to sulfur dioxide, then it's not surprising that 90% of the rats that died of liver damage died of something other than sulfur dioxide exposure. After all, only a small number of them were exposed to sulfur dioxide in the first place. (D) wins.

(A) The exclusivity of causes of liver damage is irrelevant to this study. Any of the rats could have had both causes, but only one seriously enough to cause death.

(B) explains nothing. If there is only one cause of liver disease in rats, then what killed the rats that were not exposed?

(C) As for this one, why did 65% of the exposed rats die, if environmental toxins are not very dangerous? This seems counterintuitive, and so it can't possibly help to explain the statistics.

(E) says basically the same thing as (C), with different wording. It's wrong for the same reason— namely, that it contradicts the evidence. If 65% of the rats exposed to low levels of sulfur dioxide died, then most rats probably will suffer from such exposure.

90% were not exposed to any enviromental toxin. so naturally those 65% died due to liver damage will come under the remaining 10%. As per option D entire group i.e 100% only 10% died from expsoure to enviromental toxin, which is quite low.

[quote="Bunuel"]A certain laboratory is studying the incidence of fatal liver damage in rats. Sixty-five percent of all rats whose environments exposed them to low levels of the toxin sulfur dioxide died of liver disorder. Ninety percent of all rats who died of liver disorder, however, were not exposed to any environmental toxins

Which of the following would provide a feasible explanation for the statistics above?


(A) Environmental and nonenvironmental causes of liver disease in rats are mutually exclusive.

(B) There is only one cause of fatal liver disease in rats.

(C) Environmental toxins are not particularly dangerous to the livers of rats.

(D) Only a small portion of the entire group of rats studied was exposed to environmental sulfur dioxide.

(E) Most rats will not suffer from exposure to low levels of sulfur dioxide.


(D) Only a small portion of the entire group of rats studied was exposed to environmental sulfur dioxide. Option D because it less the number to rats exposed to environment sulfur dioxide are less so we get 90 % rats died of liver disorder.......