Q13 - In 1988, a significant percentage

[peg_city]

Why is E a better answer then A?

[sukim764]

The argument states that the difference in death rate between seals in the Baltic Sea and off the coast of Scotland is "due to the higher levels of pollutants in their blood."

A does not address the discrepancy in death rate between Baltic seals and Scottish seals. E is the best answer choice because it supports the author's argument that the Baltic Sea may indeed have higher levels of pollutants than the coast of Scotland.

[timmydoeslsat]

Yep. Answer choice E gives us the presumed effect with the presumed cause.

The conclusion is causal, and this shows that the effect occurred. It shows the broad scope, as in the stimulus it was simply the seals we knew about, whereas now it is marine animals other than seals. Classic strengthener with a causal argument.

[goriano]

Yep. Answer choice E gives us the presumed effect with the presumed cause.

The conclusion is causal, and this shows that the effect occurred. It shows the broad scope, as in the stimulus it was simply the seals we knew about, whereas now it is marine animals other than seals. Classic strengthener with a causal argument.

I don't see how (E) gives us presumed effect with presumed cause. (E) does give us presumed effect (higher death rate for other Baltic Sea mammals) but the presumed cause are pollutants, not the viral diseases. Since (E) just gives us another correlation, there could have been something else responsible for the viral diseases. Could someone shed light on this?

[js_martin01]

I would have to agree with the previous poster.

The conclusion states that the higher death rate was presumably attributed to a higher level of pollutants ingested by Baltic seals. The credited answer, (E), does not address this correlation between higher incidence of death among Baltic seals and higher levels of pollutants in their blood. Instead, it focuses solely on the death rate due to viral disease.

Thoughts?

[timmydoeslsat]

You bring up great points.

It is not as strong as we normally see with a presumed cause-presumed effect situation. What this does is similar, however. If it really is the case that the pollutants are causing these issues with the seals, we would expect to see evidence that the rates of other marine mammals falling victim to viral diseases would be greater in the Baltic than Scotland.

We know what happens when marine mammals encounter pollutants: it impairs the immune system. So since we know that the Baltic seals had higher amounts of pollutants than the Scottish, we would expect a higher mortality rate of viral diseases. We still of course only have a correlation of these Baltic seals dying more often and these seals do have higher levels of pollutants than their Scottish counterparts, but we don't know what other odd things could be occurring.

So, as you guys have brought up, answer choice E does not prove the pollutants are causing the higher death rates, but it does tighten the correlation.

[anjelica.grace]

So, as you guys have brought up, answer choice E does not prove the pollutants are causing the higher death rates, but it does tighten the correlation.

Not to confuse anyone but how does tightening the correlation work here as the credited strengthener whereas the correlation answer choice (A) in question 18 in the other LR section is incorrect?

Sorry to the forum moderators, I wasn't sure where to post this particular question, but I do find the test makers being slightly inconsistent if a correlation can strengthen in this question but not in another question.

[alexg89]

I also agree with some of the other posters here that this question is not very well constructed. For instance the viral disease that is actually effecting the seals in the Baltic area could be a different more virulent strain; I was actually anticipating an answer addressing this and chose B. I see how E is supported by the line about pollutants effecting marine mammals ability to fight viral infections though but I think both could be argued to support the conclusion.

I think the test makers knew that not all of these questions were very solid and threw in a -4 curve for a 180.

[maryadkins]

Great conversation here, guys. Really smart. So you're right--sometimes when you have an argument that has this structure:

Premise: A and B are correlated
Conclusion: A causes B

... the best strengthener turns out to be an answer that just beefs up the correlation. (Like here.) Other times (like in Question 18 in Section 2 of this test), an answer that just beefs up the correlation is not the best strengthener (like answer choice (A) in S2, Q18, which is incorrect).

So what's going on?!

Here's the key: you're looking for the BEST strengthener ("most strengthens" "most strongly supports"... think about the wording). Strengthening the actual causal argument by giving us a reason why A actually does CAUSE B is always better than just beefing up the correlation ("A and B are correlated in even more ways!"). But if 4 answer choices don't even do that--if they don't address the link, at all--then the correlation-booster can be the best.

In this case, we're trying to strengthen the argument that the higher level of pollutants are what explain the higher death rates for the Baltic seals.

(A) tells us why the Scottish seals are dying, but why are the Baltic seals dying? Is it the higher pollutant level or not?

(B) tells us which of the Scottish seals are dying faster than which other Scottish seals. But what about the Baltic ones?

(C) "slight variation?" That's pretty explicit about how weak it is. Again: Are the higher pollutant levels why they're dying, or not?

(D) Kinds? We're talking about levels, not types. In fact, if "kinds" is the issue, that might explain the different death rates instead of levels, in which case this weakens the argument.

(E) Ah. If other animals were also dying in the Baltic sea due to viral infection--which we KNOW POLLUTANTS MAKE ANIMALS MORE SUSCEPTIBLE TO (because we were told so in a premise)--it gives us more evidence to support the conclusion that the high pollution levels were what was killing the seals.

For those of you looking back at S2, Q18, note that the correct answer there (B) is very clear about establishing a causal link between the premise and conclusion. It's a solid causal strengthener. We just don't have that kind of contender here.

[griffin.811]

Just to piggy back of Mary a bit, our core is essentially:

Baltic seals higher level of pollutants in blood and died at higher rate than Scottish seals--->pollutants known to impair marine mammals' ability to fight viral infection---> pollutants the likely cause of death.

*pay attention to the use of "marine mammals" vs "seals" in the conclusion.

If we know that increased pollution in the blood stream impairs the ability of marine mammals to fight off viral infection, then, if increased pollution really was the cause of death for the Baltic seals, other MARINE MAMMALS in the Baltic sea should have faced the same fate as pointed out in E.

(A) Majority of Scotttish seals that died were old/unhealthy. We dont know that the majority of Baltic seals that perished were not old/unhealthy too. If this is the case, this would be completely irrelevant. Also this does not attempt to explain how increased pollutants led to a higher level of death for Baltic seals.

(B)Which seals, if either have impaired immune systems? the passage doesn't give us this info.

(C) Perhaps this is true, but we are only concerned with the concentration of pollution in the seals that perished. Even if this is referring to the dead seals, slight fluctuations do not rule out the possibility that even those seals that were on the lower side of the fluctuation were still more polluted than the Scottish seals.

(D) This was the most tempting wrong choice to me. I was thinking, different pollutant could mean the pollution in the Baltic was stronger/more harmful than that found in Scottish waters. But the reverse could also be true. Still this could strengthen, so I deferred judgement.

D and E were the only two choices that made valid comparisons I felt, but went with E because it does not have the possibility of weakening the argument.

[roflcoptersoisoi]

The argument infers a cause from a mere correlation. The correct answer will strengthen this relationship by : shutting down a competing hypothesis for the phenomenon in question, or will attempt to strengthen the correlation.

(A) How does this relate to the pollutants that were purportedly responsible for their deaths?
(B) Irrelevant, this just tells us that seals in the Scottish sea would have died faster, this tells us nothing about the rate at which they die or the rate at which the baltic seals die.
(C) Who the hell cares? The fluctuations tell us nothing about the rate at which they died.
(D) Different in what regards? Are the pollutants more potent in the Scottish sea than the Baltic one, because if so this would weaken the argument. Too much ambiguity, this answer choice requires too much conjecture to be considered seriously.
(E) I was hesitant about this answer choice because it mentioned other mammals, but remember unlike sufficient and assumption based questions you need to be more flexible because answer that contain info that are out of scope and still affect the argument. But if other mammals were dying in an area that has been conclusively proven to have more pollutants then it strengthens the notion that the higher rate of pollutants is what actually caused a higher death rate of baltic seals.

[LeeJ891]

I found this question tricky and chose (B). If Scottish seals have a virus that impairs their immune systems, won't that strengthen the argument by showing that even when compared to a group that also had impaired immune systems (similar purportedly to those of Baltic seals who had impaired immune systems because of the pollutants), the Baltic seals STILL died at a rate double that of the Scottish seals. Wouldn't this strengthen the argument?

#help

[Laura Damone]

First, please excuse the delayed response. This one must have slipped through the cracks amidst all the craziness of the past few weeks.

Second, I believe you misinterpreted B. It doesn't tell us that the Scottish seals has impaired immune systems generally. Instead, it tells us that the virus that did kill Scottish seals did do by overwhelming their immune systems, which happened more quickly in the immunocompromised. What percentage of Scottish seals were immunocompromised? We don't know.

That means B doesn't demonstrate that Baltic seals were even more at risk than a generally immunompromised population.

Hope this helps!