if you refer to the practice question stems above, the PSA questions ask for the principle that most helps to justify rather than saying "which one of the following, if true strengthens"

The quick view feature will give you the question and ACs :)

Eradicate just means get rid of. It doesn’t mean that something that is eradicated can’t come back under certain circumstances, especially when it is simply referring to these cities in the Industrial Revolution. it doesn’t mean that the disease was eradicated everywhere, which would then constitute extinction.

i think the self defence thing is more to just say that their reaction speed is faster as a result of that part of their brain is triggered, but obviously they know that they're just playing and the goal is to catch the ball, so their conscious actions are to catch it, while the part of their brain that is triggered is simply that of tracking for the purpose of self defence and not actually for the sake of self defence.

the poverty situation matters less than the nourishment part of the stimulus in terms of helping answer the question. the answer choice that are correct in rectifying the issue are the ones that help explain why the malnourishment of the 65 + group is higher even tho they got money vs why those who are young but broke are fairly healthy. while the wrong answer choice is the one that just doesn't help answer why there's this discrepancy, or does nothing for it.

E helps in explaining this issue because it's saying that the young people don't have medical conditions which would make them malnourished, and this leads us to be like ohhh ok so that makes sense why even tho they're broke, they're still fairly healthy. D does not help to explain the discrepancy because it just has no bearing on the facts of the stimulus. it doesn't help in proving or disproving anything, whether or not the younger and older people have relatively similar chances at being poor doesn't help explain why the older ones are malnourished, nor does it help explain why the younger ones are nourished.

i thought about it like this: to record, they would have to know where they are, so when more people report the tornadoes (detect and then say something), there will be a larger record of them.

I think it is often helpful to think about "Does the stimulus every mention this" in certain circumstances. However, some answers for some question types require you to connect dots that aren't directly there in the stimulus, and so if one comes across a stimulus that is confusing, one might knock out possibly correct answers based on the fact that it is not mentioned directly.

This is obviously damaging in that case, which is why I think JY makes sure to really explain the logic behind ruling out wrong answers, to get in the habit of understanding how to process wrong and right answers beyond simply dismissing it because it is not mentioned. I don't think he expects everyone to always use the same process of breaking down the answer options, but uses this method of explanation as a worst case scenario, ensuring that you are prepared with this tool if ever confused.

A sufficient condition means that if A happens or B happens then C will occur. this means that A happening guarantees C and B also guarantees C. Or, it can be framed as necessary which i think looks like this: C will happen (C will surely come about if...) if A and B happens. this perspective requires both of those conditions to be met for C to occur, because its implying that both A and B are necessary for C to happen, but only together will they be enough (meet the requirements) for C to happen, not alone.

A sufficient condition means it is enough by itself to make something come about, whereas necessary means its important but not enough, or not the only condition needed.