#11 - A distemper virus has caused two-thirds of the seal

[yournoona]

Sometimes these also turn out to be the must be true. Please could you give me some indicators to identify between these two concepts. Also is the same given in the critical reasoning bible of gmat?

They actually don't randomly or "sometimes" turn out to be Must—there are specific reasons one would classify it as Must or Strengthen This is all explained in any of our LR/CR books. Read the chapters on question stems (especially the Families), Must, and Strengthen. I can't easily summarize it here since it's pages worth of info, but the language tells you everything you need to know!

Ok sure, will do that. Thanks!

[180bound]

Hi,

I am having trouble understanding why A strengths this argument. The past 10 years from the time I read the question would mean from 2010-2020. I don't understand how "at various times between 2010-2020...." would strengthen the argument when the stimulus says "since May 1988". I know this question was from the June 1993, could that have something to do with it because "past 10 years" would make more sense to me for this question

[KelseyWoods]

Hi 180bound!

Yes, since the question is from the June 1993 LSAT, the 10 year period applies to June 1993-June 1983. Typically, LSAT questions don't hinge on specific years so this doesn't usually become a problem when re-examining old questions.

Hope this helps!

Best,
Kelsey

[Neil J]

Hi,

Upon review, "A" makes complete sense to me. I think part of the reason I mistakenly selected "E" was because I did not understand what "distemper" meant. Is it important to know what distemper means to understand this problem? Because it certainly confused me.

Thanks!

[Robert Carroll]

Neil J,

No need to know what it is! In fact, take out the word "distemper" from the stimulus! You'd have a "virus" causing the seals to die out. That wouldn't affect anything about the argument or answer.

Robert Carroll

[a2000]

I likewise chose "E" because I read "the distemper caused by the virus" (in the answer choice) to be different from "a distemper virus" (in the stimulus) in that the virus had already been present but this disease in response to the virus is new. The stimulus language "the normally latent virus" and "could no longer withstand the virus" seemed to support this reading. On closer inspection, it could be "and so the seals' immune systems were unprepared to counter it" that undermines this interpretation of the answer choice. Was that the clue that I was misreading the answer choice? More broadly, to prevent this type of error in the future, is this a common pattern that appears in appealing but wrong answer choices?

[Rachael Wilkenfeld]

Hi a2000,

I don't think you are misreading the answer choice here. It's true that the answer choice is explaining that the distemper that the seals had experienced since May 1988 was a new strain of distemper. If that's true though, it would be an alternate cause for the increased virulence of the disease.

Our stimulus suggested that more seals are dying because of the pollution weakening the seal's immune systems. That's introducing a causal relationship---the pollution is causing the weak immune system which in turn causes the seals to die. Our question stem asks us to strengthen that relationship, which we can do by eliminating alternate causes and showing that when the cause occurs, the effect occurs. Answer choice (E) gives us an alternate cause---the virus is different than it was prior, meaning that the novel nature of the virus was the cause of the weakened immunity. That would weaken the causal relationship in the stimulus which is the opposite of what we want! Answer choice (A) on the other hand strengthens the stimulus by providing us with another situation when the cause of pollution occurred, the effect of animals dying (this time shellfish) also occurred.

Hope that helps!