Hi Rosa, I am not in Montreal but I would be interested in joining a such a group (if there was one created) and commute (if ever they decided to meet up on weekends or something). Let me know!

This is how I’ve come to understand #1 after getting it wrong (please feel free to correct if my reasoning is flawed here):

IR = Inspire Revulsion; H = Horrific; T = Threatening; PD = Physically dangerous.

A. No, because not every T is necessarily for an H (based on the scenario). You could have T and PD, without the H.

B. No, because /IR does not mean /H (and subsequently /T). You can still have H, without IR (for another reason). IR leads to H, yes, but /IR does not necessarily lead to /H.

C. No, because /PD does not mean /T, which would mean /H as well (based on the contrapositives of the chains established). The fact that you have /PD doesn’t affect whether you have (or not) H, because T isn’t affected. You could have T without PD.

D. No, because to have /IR you’d need /T ~> /H (contrapositive of the first chain). If you know you haveH, which is necessary for IR, then the chain /T ~> /H ~> /IR (which is the contrapositive of the first chain we first established in the question) does not hold. Similar to the part in option (B), we have H, which means we may or may not have IR (we could have H from the IR in the first chain, or we could have H from another reason). But there is a possibility that we DO have IR.

E. YES ~> Say you have /PD. As established earlier, that does NOT mean /T. OK. Now, you have IR, which you know leads you to H, which leads you to T. So we have one chain being followed, and another statement (PD) does not mean that we don’t have T.

Hang with me here folks, I think I figured it out:

Conclusion: deterioration of cognitive faculties associated with Alzheimer's disease is caused by microglia (i.e. brain’s open immune cells).

Why: Microglia (brain’s open immune cells) attacks protein BA deposits by releasing poisons that destroy healthy brain cells which impairs brains cognitive functions; deterioration of cognitive faculties (caused by microglia) can be slowed by acetylsalicylic acid.

Assumption: AA slows down the deterioration caused by Microglia. It doesn't stop or eliminate it, it just slows it down. It's like adding an extra step (I'm just drawing it out here):

Initially, we had Microglia --> Deterioration.

Now, it's Microglia --> (AA) --> Deterioration.

How does AA, when slowing what is caused by Microglia, still reinforce the idea that Microglia still leads to deterioration (conclusion)?

• Microglia = brain's open immune cells. OK.

• AA = slows down the process of brain’s open immune cells --> deterioration, but still can/leads to deterioration.

Answer choice B --> Acetylsalicylic acid reduces the production of immune cells in the brain } So REDUCING the production of brain's open immune cells makes it so that there is LESS of them, so it won't lead to the deterioration as quickly, right? Logically: more bad/good cells = more reproduction of said cells; if brain’s open immune cells lead to deterioration, and this chain/process is slowed by AA, it makes sense that AA makes it so that there are LESS brain’s open immune cells (microglia).

So we have a lot of microglia (i.e. brain’s open immune cells) which leads to deterioration of faculties; taking AA slows this process (it doesn't stop or eliminate it). How can it do that? Well, logically, it has to impact Microglia somehow, if it makes longer to get from A (microglia) to B (deterioration). Answer choice B tells us: AA reduces number of Microglia = YES, there are less brain’s open immune cells, but this lower number still leading to deterioration REINFORCES the notion that those cells that were not reduced (which are still Microglia) by AA led to the deterioration of cognitive faculties.

Conclusion: Last year’s mild winter reason for larger bird population.

Why: it was mild for bird to forage naturally and not visit feeders; they stayed home in summer range without migrating south.

Assumption: it's a strengthening question - we know that mild winter made it easier for birds to forage naturally... but what makes it so that foraging naturally (versus eating at feeders) is ALSO/ADDITIONALLY beneficial (other than the fact that the winter was mild)?

---> Answer choice C: eating at feeders = more dangerous because of predators; foraging naturally = easier because of the winter (milder makes it easier), but ALSO because it's safer (less vulnerable to predators).

Conclusion: children in large families (youngest) = fewer allergies than kids in small families

Why (support): exposure to germs makes people less likely to develop allergies

Assumption (when looking for answer): being exposed to many people develops resistance to developing allergies

AC E says that if children (small families) enter day care before age one, you're less likely to develop allergies than if you enter later --> Exactly, that's why children in large families have fewer allergies (being exposed to many people allows kids to develop resistance and not get the allergies later on) [applicable to both small families and large families]

Think of it this way:

Conclusion: Sunscreen is UNLIKELY to reduce risk of skin cancer

Why (support): over 25 years, skin cancer incidences have increased despite people using sunscreen.

Assumption (or how to analyze this): sunscreen COULD, in fact, help reduce skin cancer; people may get skin cancer for reasons beyond just using (or not) sunscreen [i.e. people may use sunscreen and still get cancer for other reasons]

Answer choice B (paraphrased): "old people develop skin cancer because of sunburns they got when they were young" --> Exactly: people develop skin cancer because of things like Age and Old sunburns, so whether they use sunscreen is irrelevant (they are still more susceptible; the fact that one in this category could use sunscreen and (God forbid) still get cancer isn't due to the sunscreen being ineffective, it's because they had a pre-existing condition..

I went above the timeline, more than double, and it was suggested to me to review on BR (figured I got my actual take wrong picking A, but stuck with my answer after re-reading the other options and got it right). This will be a mouthful, but here's how I went about it (feel free to correct if I am mistaken):

A = Small experimental vacuum tubes

B = Operating in heat

C = Semiconductors components fail

D = Component's comparable to semiconductors in all other categories (like max capacity)

E = Resistance to heat greater to semiconductors

F = Preferable to use in digital circuits

First sentence we can construct: A --> B --> C. OK.

Second sentence: D AND E --> F, and the reasoning is as follows:

Any component whose resistance to heat is great to that of semiconductors (E) would be preferable for use in digital circuits (F) [so here we have E --> F], but only if that component (from E) is also comparable to semiconductors in all other categories (like max capacity) (i.e. D); this means that E --> F only if D also happens, hence D AND E --> F).

Taking the contrapositive of both:

/C --> /B --> /A } Semiconductor components don't fail --> DOES NOT operate in heat --> IS NOT Small experimental vacuum tubes. OK.

/F --> /E OR /D. } What does this mean?

NOT preferable to use in digital circuits --> (NOT resistance to heat greater to semiconductors OR Component's NOT comparable to semiconductors in all other categories (like max capacity)). OK.

Last sentence says that Vacuum tubes' maximum current capacity is presently not comparable to that of semiconductors. So this is /D. What can we draw from /D (based on what I described)? That if F is false (i.e. /F), then at least one of E or D is False (i.e. either /E or /D) [It’s not that /F causes either /E or /D; it’s that if /F is true, at least one of /E or /D must be true, meaning that knowing we have /F leads us to know we for sure have either /E or /D].

Option A (in the Answer) tells us that "Vacuum tubes are not now preferable to semiconductors for use in digital circuits" = this is /F that I mentioned. That said, we don't know whether /E occurs (i.e. whether the component DOES NOT have resistance to heat greater to semiconductors), so we can't conclude /E or E.

Knowing that it is /F --> /E or /D, you can tell that based on the last sentence of the stimulus (i.e. /D), and Option (A) [of the answers] giving you /F, that based on this chain, Option A is the right answer.

A) The human body processes the beta-carotene present in foods much more efficiently than it does beta-carotene supplements.

• (A) This tells us that the beta carotene foods are processed more efficiently in the human body vs. the supplements so this definitely explains why there is a change in results. EXPLAINS DISCREPANCY (difference between processing of beta-carotene depending on what you consume: foods vs. Supplements).

B) Beta-carotene must be taken for longer than 12 years to have any cancer-preventive effects.

• (B) This focuses in on the different dates of the study, if beta carotene needs to be taken for longer than 12 years, then that explains why there was no effect in the second study. EXPLAINS DISCREPANCY (study 2 is flawed; study 1 was 24 years long and people saw results; study 2 was 12 years long and there were no results, maybe it needs to be taken longer than 12 years).

C) Foods rich in beta-carotene also tend to contain other nutrients that assist in the human body's absorption of beta-carotene.

• (C) Gives another factor that is present in the foods rich in beta carotene that the supplements do not have. EXPLAINS DISCREPANCY (foods (study 1) are different from supplements (study 2); why? —> because they have other nutrients that assist in the absorption; subsequently leads to different results).

E) In the 24-year study, the percentage of the subjects who had a high intake of beta-carotene-rich foods who smoked cigarettes was much smaller than the percentage of the subjects with a low intake of beta-carotene-rich foods who smoked.

EXPLAINS DISCREPANCY: Let’s assume that AC (E) is TRUE, and look at Study 1 (24 years long): From the answer choice, what do we know?

• % of Smokers with a High intake of BC = LOW } they are smokers, but they have high BC, so that makes them less likely to die from Cancer/Heart Desease.

• % Smokers with low intake of BC = HIGH } so they are MORE likely to die because of low BC intake. But they are also smokers, which also causes death because of cancer. So are they more likely to die from Smoking, or low BC? We don't know, and we can't tell!

• Therein-lies the discrepancy. The 24-year old study has smokers which have low intake of BC = so they are more likely to die. But it could be because of smoking! Or more because of smoking than low BC intake!

D) In the 12-year study, half of the subjects were given beta-carotene supplements and half were given a placebo.

• What does this do to solve the discrepancy? The only thing that we may incur is whether the studies were or were not controlled; assuming that both were controlled, this doesn’t solve the discrepancy.

Premise: If you're in NYC, you are in the USA. (NYC -> USA)

Conclusion: Does this mean then that, if you're in the USA, you're in NYC? (i.e. USA --> NYC)

Clearly not: because being in NYC is enough for you to know (sufficient condition) that you're in the USA.

And, by the same token, being in the USA is a requirement (necessary condition) to be in NYC (i.e. you can't be in NYC without being in the USA).