The argument says that because 2 species of birds have the virus in the exact same spot on their chromosomes, and the birds diverged 25 million years ago, that the virus is at least 25 million years old.

Gap: is it possible that the birds both acquired the chromosome at some point more recently?

(A) is attractive, but wrong. It requires an assumption that could go either way. It says "Viruses can affect the evolution of an organism and thereby influence the likelihood of their diverging into two species"

But does it make it MORE or LESS likely? We don't know. If it makes it more likely, that would strengthen a little. But if it makes it less likely, that would weaken the argument.

(C) says "When the virus inserts itself into an animal's chromosome, that insertion occurs at a random spot." (C) is correct because it dispels the possibility that both species acquired the virus at a later time. It would be very unlikely that the insertion would happen in the exact same spot if it's random! (C) strengthens the argument that the birds acquired it before they diverged (that explains why it's in the same spot) and thus that the virus must have existed before that divergence, supporting our conclusion that the virus must be at least 25 million years old.

Q21: (E) and (B) are both getting at the second paragraph, and speak to whether theoretical equipoise is possible (they are suggesting that it is). But this question is about the third and fourth paragraphs specifically, which deals with clinical equipoise.

If (A) is true, there is usually a preexisting consensus in the medical community about the best treatment. This is not great for clinical equipoise, which mandates that there be a lack of consensus among experts. That's why (A) weakens the argument in the third and fourth paragraphs

Q17: I initially chose (A) because it was specific to Mesolithic people. However, it does not speak tot he author's proposal about WHY the paths were established, which is all we care about on this question. (A) traps us by being specific to the Mesolithic era and talking about the same topic as the second-to-last paragraph, but it doesn't help support the author's proposal about fear of the woods motivating path-making.

I didn't like (E) because it talks about "certain recent premodern populations" rather than people from the Mesolithic era. I thought it would be an unfair jump to assume these populations were Mesolithic, but we actually don't really have to do that. The previous paragraph about Yi-Fu Tuan says "such fears [of the wilderness] are...manifest in preliterate and nonurban societies," suggesting it applies to premodern societies like those in the Mesolithic era, but also many others. (E) is also the only answer choice that specifically addresses the author's proposal about fear of the wilderness, and would show that it does apply to an old society, presumably closer in time to the Mesolithic than present-day society.

(D) is correct because it speaks to the blood/bone comparison issue. It would be even better if it spoke to the old/new comparability (have the ancient bones deteriorated in a way that affects their heavy nitrogen levels?) but (D) does strengthen the idea that blood samples and bone samples are comparable, albeit only within present-day bears.

I didn't like (E) because of the word "assumed" -- I thought that because the author said "economists reason that..." that we could trust the author to be reporting a cold hard fact about economists' reasoning.

(E) saying the author took their reasoning to be assumed felt like it denied the fact that it was explicitly stated in OPA. But we didn't hear this reasoning directly from the economists, and we can't trust that the author is reporting on what they would argue with 100% accuracy. So the author does "assume" the reasoning it rejects, and it would still be accurate to say so even if we heard OPA directly. Here, it just makes more sense to say it's assumed because we're hearing both sides from the consumer advocate.

I thought Kumar wouldn't be cited as late because it didn't say he's a student, lol.

C addresses a factor D doesn't: the other factors in the report. That's why I found it attractve.

But D speaks to something more fundamental (and thus more useful in evaluating the argument): does the change in tax filing for small and midsized businesses translate to the report's results? I see this as an analogy: are these small/midsized businesses analogous enough to the report's hypothetical one that this will increase the ranking?

If D isn't true and the small/midsized businesses aren't similar to the report's business, then the change in tax filing doesn't matter. Boom. Argument destroyed.

If D is true and the small/midsized businesses are similar to the report's business, then the change in tax filing is more likely to increase their ranking. Boom. Argument strengthened.

Further, if D isn't true, C doesn't matter either. That's why it's more important for evaluating the argument than C.

If D isn't true and the businesses are disanalogous, the other factors impacting the small/midsized ones (which C talks about) won't impact the report either.

A and B both definitively deal with the urban pollution dispute. I liked B better because it seemed more definitive.

I initially didn't like A because "generally" didn't seem strong enough, and it requires us to assume that "urban pollution" is tied to "major cities" strongly enough (I thought "do all urban areas have to be MAJOR cities? What about regular cities?).

A leaves open the possibility that there are some major cities with power plants nearby where their increased pollution will be problematic.

Here's how I figured it out:

If A is true, adopting electric vehicles would reduce urban pollution a TON in most cities. It eliminates vehicle emissions and power plant emissions. There might be some cities where there's a power plant nearby, but not many.

If B is true, adopting electric vehicles would reduce urban pollution SOMEWHAT because while we pretty much get rid of car emissions, power plant emissions are still part of the equation. And they've increased!

A gets rid of 2 pollutants for MOST urban environments. B only gets rid of 1 (vehicle pollution). So overall, A would reduce more urban pollution.

E tripped me up because I thought it was assuming that there affirmatively exists a theory which conform to PP and is acceptable. The stimulus doesn't provide any affirmative evidence that this exists, and in fact only provides an explicit example of exactly the opposite: that (in the domain: retrib theories) acceptable → conforms.

From the stimulus, I mapped out my lawgic like this:

Rule:

acceptable → rehab or retrib

(note the embedded conditionals:

acceptable and rehab → retrib

acceptable and retrib → rehab) - this becomes important in E.

The stimulus further tells us:

(domain: retrib. theories)

acceptable → conforms to PP

conforms to PP → acceptable

E says:

(domain: conforms PP)

acceptable → rehab

Remembering the embedded conditional (acceptable and retrib → rehab): E is asking us to consider a hypothetical theory of sentencing which is acceptable and conform to PP. This is hard because we have no evidence that such a theory affirmatively exists. But for E to be correct, it doesn't necessarily have to exist.

More importantly, if such a theory does exist (acceptable and conforms PP), what can we say about it for sure? That it is NOT an acceptable retrib theory.

Remembering our embedded conditional (acceptable and retrib → rehab), we can conclude that if that theory exists, it is not retib, and therefore it would have to be rehab.

This was hard for me because that theory doesn't have to exist at all, and we have no evidence that it does.

Something that helped me was being told that implied questions are NOT asking you to speculate about what the author might agree with. Don't try to guess what you think the author might say, choose an answer based on what they actually said.

That can be especially tough when the correct AC is linked to a higher-level feature of the passage or seems unsupported because it's just not explicitly stated (I think PT135 S3 Q16 is a helpful example of this [https://classic.7sage.com/lsat_explanations/lsat-135-section-3-passage-3-questions/]). When in doubt, POE--especially when it feels painful!

Some moral attitudes are universal.

Some tastes are universal.

^ This maps moral attitudes onto taste ^

Some of these universal tastes (moral attitudes) can provide the basis for many cuisines

(ANTICIPATE: We need to map the many cuisines onto our many moral codes)

(C): A variety of moral codes can be based in shared moral attitudes

Just as shared basic tastes provide the basis for different cuisines, shared moral attitudes provide the basis for different moral codes.

They take basic things (sweetness, being against killing) and make them into many different moral codes (flan and ice cream are both based in sweetness, just as U.S. and Dutch murder laws are both based in being against killing).

(A): The language "tend to be" doesn't match the stimulus. We don't have anything about tendencies, just cold hard rules about how shared attitudes provide the basis for different codes

(B): "resemble each other in many respects" - no, we only know about one way they might resemble each other (shared attitudes)

(D): "possible to understand the basis" - could be somewhat supported, but this has nothing to do with the analogy we're trying to complete

(E): "moral attitudes can be adapted" - no, the attitudes are what stay the same. They're universal. The moral attitude "killing is bad" isn't adapted to fit U.S. anti-murder law, it's the basis for that law. That attitude isn't being adapted.