If the conclusion is true,then frequent use of tranquilzer inhibits fertility.We need to check how frequently it used.

Option C helps us to analyse that for other reasons also the tranquilizer is used.If tranquilizer is used for othere reasons,then it is used on female rhino more often which supports the conclusion.

Option D is providing fact abt male rhino which is not valid to analyse the argument.

No Doubt C is totally RUBBISH ANS...!

but it is correct only b'coz

all other u can say that they are clearly wrong, whereas C is not clearly wrong... !

but ofcourse how it leads to correct ans.. God only knows...!

Suggestion : by putting ans. in advance makes people BIASED towards it...!

I am not completely convinced with C though there is no other option that comes closer to the conclusion.

C says: "How often park rangers need to use trangquilizer dart to immobilize rhinoceroses for reasons other than attaching radio collars. "

If trangquilizer dart is used for reasons other than recollaring, then it must be used on both "collared" and "uncollared" female rhinoceros..

In that case the conclusion: "Female rhinoceroses that have been frequently recollared have significant lower fetility rate than uncollared females." will not be best supported. Infact it doesnt affect the conclusion much..

btw.. can somebody explain what is radio collar...? what is its use... ? for the sake of info...

The author concludes that the tranquilizer inhibits fertility. His evidence is that female rhinoceroses that have been recollared and thus tranquilized are infertile while uncollared females are fertile. For the author's conclusion to be valid, we have to assume that uncollared females haven't been tranquilized. If they have been tranquilized for whatever reason, then the difference in fertility must be attributable to something other than the tranquilizer.

Choice C is correct because if it turns out that ALL rhinoceroses (including uncollared ones) are frequently tranquilized, then the difference in fertility must be attributable to something other than the use of tranquilizers. If, on the other hand, tranquilizers are only used on collared rhinoceroses, then we've found a difference between the two groups that correlates with the difference in their fertility rates.

(Note that another issue in the author's conclusion is that he assumes a correlation between infertility and the use of the tranquilizer means that the tranquilizer causes infertility. What if it turns out that something about being infertile causes rhinoceroses to induce the use of tranquilizer?)

The larger point here is that when you're addressing the usefulness of information in evaluating an argument, you should take each of the choices to their extremes and see whether that extreme will affect the validity of the argument.

Choice D is not correct because male rhinoceroses are irrelevant to the author's conclusion.

san2009 wrote: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.

OA is C.
Why is D wrong? And more importantly, how is C relevant to analyzing that the "tranquilizer inhibits fertility??

I discussed this question and posted 2 explanations very recently right here:

https://www.beatthegmat.com/gmatprep-par ... 26671.html

...please use the search function before posting.