This is a weakening question, since the question stem demands: Which one of the following, if true, most seriously undermines the conclusion that change in the direction of the Earth’s magnetic field happened very slowly?
The stimulus begins with the conditional indicator when, and tells us that whenever lava solidifies, it necessarily magnetizes in the direction that the earth’s magnetic field points at the moment of solidification. Interesting! The next sentence gives us some more information about this event, namely that lava flows from different volcanos that erupted at different points over the past several million years are magnetized in different directions. From this evidence, the next sentence concludes that the direction’s of the earth’s magnetic field has changed over time. Seems like a fairly reasonable conclusion! The next sentence begins with the support indicator since, and whenever we see a sentence that takes the form “since X, Y”, we should expect X to be the final premise introduced before the conclusion Y. That’s exactly what we get here. The final premise tells us that lava flows that are separated by only a few thousand years have very similar magnetization directions. Based on this and our sub-conclusion from the last sentence, the stimulus ends with the main conclusion that the direction of the Earth’s magnetic field changes gradually. Our job is to select the answer choice which most weakens this conclusion; we want something that suggests non-gradual change. Let’s anchor ourselves in the argument, and consider the implications of the answer choices:
Answer Choice (A) This answer might be tempting because the movement of the liquids is described as chaotic, but there’s no reason why a gradual change couldn’t have a chaotic cause.
Answer Choice (B) If anything this answer would suggest gradual change, since we have not detected any real change during the short period we have been monitoring the field.
Answer Choice (C) The problem with this answer is that we don’t know what a complete reversal means in this case; maybe it was a very small change. And even if it was a significant change, it occurred over a long time period (a few million years), so it could still be entirely consistent with gradual change.
Correct Answer Choice (D) This answer does what C fails to; it introduces a significant change in a short timespan. A significant change in the span of weeks is completely inconsistent with a theory of gradual change over thousands of years.
Answer Choice (E) This answer is just entirely irrelevant to the gradual change theory we want to undermine. Who cares how long some lava flows will take to solidify, we want to know whether the magnetic field the point to is changing rapidly!
This is a weakening question, which we should recognize as the question stem says: Which one of the following, if true, most seriously weakens the argument?
The stimulus begins by informing us that stress is not one of the primary complaints of workers. Following this context, the author cites a recent survey in which boredom was listed as the main complaint of a majority of workers. Based on this survey, the author concludes that job-related stress is not the most serious problem for workers. Our job is to weaken this conclusion. One thing we should notice is that the support concerns what workers complain about, while the conclusion is about what the most serious problem for workers is. Surely it's possible to not complain the most about something even if it is your most serious problem! Let's see what the answer choices have in store for us:
Answer Choice (A) We are interested in whether there is a reason to assume that stress is the most serious problem workers in the corporate world face. This only tells us that a particular subset of workers is less likely to complain about stress than are workers as a whole.
Correct Answer Choice (B) If boredom correlates with stress, and a majority of workers complain of boredom, then we have a reason to believe that the study the author cites actually suggests that stress might be the most serious problem workers face.
Answer Choice (C) This answer may somewhat weaken the accuracy of the survey, insofar as workers may be exaggerating recent experiences of boredom, but it does so in a fairly minor way, and the survey being somewhat poorer evidence does not significantly weaken the argument as a whole.
Answer Choice (D) This just tells us about a subset of workers and how they complain about boredom. There is nothing here for us to work with to weaken the argument's actual conclusion.
Answer Choice (E) Seems reasonable, but I don't see how this would weaken the conclusion that stress is not the main problem for corporate workers. We are interested in stress, not the relative tendency to complain.
We know this is a resolve reconcile explain question, because it asks: Which one of the following, if true, most helps to explain why the agricultural peoples of western Asia never returned to hunting and gathering?
The stimulus begins with some context; ten thousand years ago many of the communities in Western Asia switched from hunting and gathering to agriculture. Interestingly, this lead to poor diets and health issues, yet the people never returned to hunting and gathering. Our job is to explain why the communities stuck with agriculture when all we know so far is that it made their lives worse. A good answer choice will give a reason for their committal to agriculture that is compatible with the health effects mentioned in the stimulus. On to the answers:
Answer Choice (A) This doesn’t explain their committal to agriculture, it actually just makes the situation stranger by explicitly stating hunting and gathering food was still an option.
Answer Choice (B) Interesting! But this feature of both food methods doesn’t explain the committal to one over the other.
Correct Answer Choice (C) Here we go, this gives us a reason why hunting and gathering food just wasn’t going to cut it anymore, even if agriculture had negative trade offs. If one option isn’t going to work anymore, then sticking to the other makes sense.
Answer Choice (D) This tells us the phenomenon was widespread, but doesn’t provide an explanation for why it occurred in the first place.
Answer Choice (E) This just seems like another downside to agriculture, which makes the committal of the communities even less intelligible.
Here we have a resolve reconcile explain question, since it asks: Which one of the following, if true, most helps to resolve the apparent discrepancy?
Our stimulus begins by telling us that Mr. Young has the highest rate of unsuccessful collections at a collection agency. However, he is the best bill collector the agency has. The discrepancy is that we would expect a good bill collector to have less unsuccessful collections. We want to resolve this discrepancy by finding an answer choice which explains why Mr. Young might have a lot of unsuccessful collections in a way that is compatible with him being the best bill collector. Let’s see what we get!
Correct Answer Choice (A) This does exactly what we want! It would make sense that the hardest cases go to the best bill collector, and that the difficulty of these cases would lead to more unsuccessful collections.
Answer Choice (B) That’s very nice of the other bill collectors, but their opinions don’t do anything to explain why he has so many unsuccessful cases!
Answer Choice (C) Interesting! But again, his rate of collections remaining constant doesn’t explain a high rate of failed collections compared to others.
Answer Choice (D) Save it for his biography, this does nothing to help us!
Answer Choice (E) This just gives us another reason why we’d expect him to have a lower rate of unsuccessful collections compared to his juniors.