#8 - This boulder is volcanic in origin and yet the rest

[goingslow]

Thank you, Adam!

[supjeremyklein]

(d) isn't only talking about 'current' geo-sources, it's talking about NO geo-sources at all ... past / present. if there are no current geo-sources but there are past geo-sources, that means a geo-source was identified. (d) says NO geo-sources. that means NO geo-sources (current/past).

[Robert Carroll]

supjeremyklein,

Actually, answer choice (D) uses the present tense "are" which means we can't be sure whether this has always been the case. That's why, as Adam points out, answer choice (D) weakens the argument without absolutely destroying the conclusion. Because weakening the argument is good enough to make an answer correct for a Weaken question, that's fine!

Robert Carroll

[lsatep2024]

Hi,

I see how Answer choice (A) is explained through the use of the "most" modifier, but I wanted to clarify if it also didn't work since in a way, the fact that most boulders don't move that much doesn't affect this specific boulder in the context of the stimulus!

[Adam Tyson]

That's correct, lsatep2024. This boulder doesn't have to be like most boulders. In fact, what if 49% of all boulders moved by glaciers were moved more than 100 miles? Then there would be no reason to doubt this argument! But even if it's just one boulder, once in a great while, that still could be okay. As I mentioned earlier in this thread, I held onto answer A as a contender, because it did make me think "well, that would make this boulder something of an outlier or surprise, so maybe that's a reason to feel some doubt about the conclusion." But when I got to answer D, it was so much more powerful than answer A, pretty much disproving the theory in the argument. Since we are supposed to pick the answer that most seriously weakens the argument, that let me know that A was no longer worth considering.