In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars. When, as often happens, a collar slips off, it is put back on. Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart. Female rhinoceroses that have been frequently recollared have significant lower fetility rate than uncollared females. Probably, therefore, some subtances in the tranquilizer inhibit fertility.
Inevaluating the argument, it would be most useful to determine which of the following?
a. Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park.
b. How the tranquilizer that is used for immobilizing rhinoceroses differs, if at all, from tranquilizers used in working with other large mammals.
c. How often park rangers need to use trangquilizer dart to immobilize rhinoceroses for reasons other than attaching radio collars.
d. Whether male rhinoceroses in the wild park lose their collar any more often than the park's female rhinoceroses do
e. Whether radio collar is the only pratical means that park rangers have for tracking the movements of rhinoceroses in the park.
I have no doubt about the correct choice because it exploits the flaw in the argument.
But I still have a doubt about choice A.
The author makes a comparison between the fertility rates between 2 groups to support his conclusion. If there are 1000 recollared rhinos and 10 uncollared rhinos, and the fertility rates are 50% and 80% respectively, so we have 500 fertile recollared rhinos and 8 fertile uncollared rhinos.
if the difference between numbers of the two groups are too large-- i.e. 1000 and 10 -- and if we accept the author's assumption that the only purpose to shoot rhinos with T darts is to put collar, does the comparison between the fertile rates support the conclusion?
I must ask the question because before I see the correct answer I did not know the flaw of the argument, and the choice A seems good to me. So, if I know the answer for the question, I can eliminate choice A.