Paleontologists recently discovered teeth from several woolly mammoths

we have to somehow link the claim made about teeth size with size of mammoth. choice (B) doesn't do that, rather it goes on talking about tooth wear
(D) fits the gap better in the assumption required

pretty good lsat question, you sure know how to pick the good ones

D is not redundant, actually, the very fact that it is an assumption that the author made is WHY its the correct answer.

The statement:
'provided that teeth are representative of their respective populations'
Is not the same as:
'provided that teeth are representative of the sizes of their respective populations'

B is a statement about ALL woolly mammoths. All B does is show that the size of the teeth found by the paleontologists is the actual size of the mammoths in each population. This but this still doesn't allow the conclusion to be properly drawn, since we would still need to assume that tooth size is similarly proportionate to mammoth size across all mammoth populations

For this type of question, i think i have spotted the pattern of choosing the obvious one. I do not think the real gmat is that way though

Initially picked B but realized it is irrelevant. It has no effect on the conclusion upon negation.

D fits well.

Argument : Paleontologists found 25% smaller size teeth of adult woolly mammoths.
Conclusion : Overall Size of Woolly Mammoths is less than on average compared to the mammoths elsewhere

D) Tooth size among adult woolly mammoths was directly proportional to overall size of those mammoths.
This option is comparing the size among the woolly mammoths.

Whereas in option B) The teeth wear didn't decrease the size of the teeth of adult woolly mammoths significantly.
if negated, the teeth wear did decrease of the teeth size of the woolly mammoths significantly which breaks down the conclusion.

Any pointers?

Which one of the following, if assumed, would allow the conclusion to be properly drawn?


(A) Neither tooth size nor overall body size is completely uniform among adult members of most species, including woolly mammoths.

(B) The tooth wear that naturally occurs in many animals over the course of their adult years did not result in a significant change in tooth size among adult woolly mammoths as they aged.

(C) Unusually small mammoth teeth found at locations other than the island have always been those of juvenile mammoths rather than adult mammoths.

(D) Tooth size among adult woolly mammoths was always directly proportional to the overall size of those mammoths.

(E) Woolly mammoths of the kind that lived on the island had the same number and variety of teeth as mammoths that lived elsewhere had.


We are concerned with Tooth size of woolly mammoth and its population.

Only D is relevant.

Paleontologists recently discovered teeth from several woolly mammoths on an isolated Arctic island where no mammoth fossils had previously been found. The teeth were 25 percent smaller on average than adult mammoth teeth that have been found elsewhere, but they are clearly adult mammoth teeth. Therefore, provided that the teeth are representative of their respective populations, woolly mammoths that lived on the island were smaller on average than those that lived elsewhere.

Which one of the following, if assumed, would allow the conclusion to be properly drawn?


(A) Neither tooth size nor overall body size is completely uniform among adult members of most species, including woolly mammoths. - WRONG. Complicates matter more than helps the conclusion.

(B) The tooth wear that naturally occurs in many animals over the course of their adult years did not result in a significant change in tooth size among adult woolly mammoths as they aged. - WRONG. Key is that it happen when they were alive.

(C) Unusually small mammoth teeth found at locations other than the island have always been those of juvenile mammoths rather than adult mammoths. - WRONG. Irrelevant.

(D) Tooth size among adult woolly mammoths was always directly proportional to the overall size of those mammoths. - CORRECT.

(E) Woolly mammoths of the kind that lived on the island had the same number and variety of teeth as mammoths that lived elsewhere had. - WRONG. Not necessarily needed. Irrelevant.

Answer D.

Let me try to explain Why B is wrong?

(B) The tooth wear that naturally occurs in many animals over the course of their adult years did not result in a significant change in tooth size among adult woolly mammoths as they aged.

Even when tooth wear result in significant change in adults then wear will be similar in both kind of adults and their relative size may not change at all. Hence it will not hurt our conclusion.

I hope that helps!!