Although exposure to asbestos is the primary cause of mesothelioma, a

Dear SamuelWitwicky,
I'm happy to respond. Thank you very much for you kind words. I must say, I feel a little humbled by the comparison to Bunuel, whom I hold in tremendous respect.

What you ask is an excellent question. Here's the prompt again:
Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cancer, researches believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus. Researches hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

Which of the following, if true, most strongly supports the researchers' hypothesis?

(A) SV40 is widely used as a research tool in cancer laboratories.

(B) Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.

(C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

(D) In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.

(E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

Here's what I think about (B). The hypothesis is that the contamination of the polio vaccine with the virus SV40 contributes to the incidence of mesothelioma. We don't know whether this is true: the researcher think that this is true, and we are asked to strength this conclusion.

If that conjecture were true, then it would be a problem, and (B) would be an excellent solution to the problem. But we are not asked to solve the biological problem discussed: we are asked to strengthen the conclusion. Furthermore, we don't have any additional information. The prediction of the researchers would be that if we changed the vaccine manufacturing technique, eliminating SV40 contamination, then we would expect the incidence of mesothelioma to drop. If we were told all this, then that would be incredibly strong evidence for this conjecture. The problem is: we are not told the result. We are told only that SV40 has been eliminating from the vaccine manufacturing process. Then what happened? Frustratingly, we are not told. The results of this change could be a huge strengthener, but we are not told this. That's the problem with (B).

We can't really make inferences from the manufacturer's motivations. First of all, when a group of scientists speculate that some X is a risk, a lot of people just start avoiding X because it could be a risk, even though sometimes it turns out that this X is perfectly safe. The manufacturers might have caught wind of the scientists' speculation and simply believed them because they are scientists, irrespective of the validity of the conjecture. Furthermore, it is quite likely that the manufacturer made a change that eliminates not just SV40 in particular, but a number of viruses --- for example, some kind of intense heat or flash pasteurization, something that would destroy virtually all viruses. The manufacturers could have made this change on general principles, without any knowledge at all about SV40 in particular. We simply don't know.

Does all this make sense?
Mike

Category – Strengthen (Cause & Effect)

Premise-1: Primary cause for mesothelioma is asbestos BUT SV40 virus ALSO contributes.

Premise-2: In 1960, vaccine was contaminated with SV40.

Conclusion: Vaccine (cause) => virus in mesotheliomas (effect)

Correct choice can be in any of the follwoing forms:
#1. A choice that says there is no other cause for the above effect. OR
#2. A choice that says there is no other effect for the above cause.
#3. A choice that says there is no cause for the above cause.
#4. A choice that says if no cause then no effect.

A) SV40 is widely used as a research toll in cancer laboratories.
If a cancer laboratory uses SV40 then we are not sure about the connection of this usage with vaccine having SV40.

B) Changes in the technique of manufacturing the vaccine now prevent contamination with SV40
Weakner. It says vaccine cannot have SV40, so what researchers are saying is wrong. Had the question asked for weakner this would have been the correct choice.

C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
This is rephrase of the premise “1960 some polio vaccine was contaminated with the virus”. We need a new evidence to support the conclusion. So what already is stated cannot be the answer here becauseThis is not an “coclusion” or “inference” question.

D) In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
argument says that asbestos is primary cause but SV40 virus also contributes. But does this any says that vaccine causes mesotheliomas? No!

E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40
This is parallel to “if no cause then no effect.”. - CORRECT

The answer is an easy E once you know the rule of the game.
This is a particularly good question that underlies the importance of understanding the rules for CR.

This is a strengthen the conclusion question:-
Now imagine this conversation
You:-Hey Bob, .. I think superman is the most powerful hero
Bob :- Why do u think so ?
You:- Because Superman can fly, stop bullet, reach the sun and breathe underwater.
Bob:- I am still not convinced. Tell me one more thing that superman can do.

Now think what your answer would be :-
Superman once touched an elephant and the elephant fell 5000 feet away.
OR
Superman can fly very fast and very high.

Now Bob has asked you to strengthen your conclusion about superman. He is not convinced with the four reasons that you already told him. He needs one more reason to believe your conclusion. So you must present a NEW REASON to make your conclusion stronger. You cannot state the same reason that you have already presented to him before.


THIS IS WHAT OPTION E IS DOING.
E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40
Option E apart from all the old information, already present in the stimulus, is giving another information that is making our conclusion stronger

OPTION C is wrong because it is repeating what is already said in the stimulus
C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

But we already know that .. don't we ?? the question stem contains this info explicitly :-"in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was the source of the virus."

SO we need a new proof to make our conclusion stronger.







Although exposure to asbestos is the primary cause for mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing case, since in the US 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

Which of the following, if true, most strongly supports the researchers' hypothesis?

A) SV40 is widely used as a research toll in cancer laboratories.
B) Changes in the technique of manufacturing the vaccine now prevent contamination with SV40
C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
D) In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40

Premise : SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus.
Conclusion : Reseachers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

Cause → Effect

SV40 → polio vaccine contaminated with mesotheliomas



Answer : (E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas DO NOT contain SV40.

I have a real problem with this answer. E doesn’t support the contention that SV40 is a contributor to mesothelioma. It actually undermines that conclusion by finding cases where SV40 plays no role.

Posted from my mobile device

One of the Good ways GMAT Lays trap is just repeating the Premise in a Polished manner.

Option C does that, and if we are not cautious we may end up marking the Wrong answer choice which is C.

However E is the correct answer as it is directly weakening the conclusion.

Simple yet effective way to eliminate option C

Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

I have seen this pattern in many gmat questions. Gmat relies on you to assume that the vaccine we talking about in option C is the polio vaccine. It just says vaccine. It doesn't mention whether the vaccine was polio vaccine or any other vaccine. It could have been any other vaccine

And hence qualifies as one of the most effective gmat traps

otherwise this question is pretty straightforward

its a cause and effect strengthener

one way to strengthen this is by showing that when there was no cause there was no effect

In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

Conclusion: this vaccine was the source of the virus found in mesotheliomas decades later.

(C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

This one strenghten the presence of the virus in the vaccine, but is not strenghtening the fact that this vaccine is the source of the virus.

(E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.\

Certainly, the absence of the effect where the vaccine was never contaminated strenghtens the fact that the virus from the vaccine was the source of the virus foun in mesotheliomas.

Best,

i will try to be as basic as possible in terms of explanations.

@experts if you feel that i am incorrect or I am not precisely correct, please feel free to correct me

option A : irrelevant - we need to strengthen the hypothesis that the vaccine that got contaminated in 1960 was the source of the virus sv40 in mesotheliomas. This option is doing nothing along those lines. Also, this option just kinda proves that there is some sort of connection between cancer and sv40, but does nothing in terms of making the hypothesis more believable.

option B : irrelevant - so now the manufacturers of the vaccine have made a few changes in technique of manufacturing the vaccine that doesn't let the virus get in. Awesome, but then again. We really want to make the hypothesis more believable, but does nothing in terms of making the hypothesis more believable - we know this is for a fact that the some vaccine in 1960 got contaminated with the virus, what the manufacturers are doing now to prevent such a contamination is completely irrelevant.

option C : This actually is a classic trap option While reading the argument, it is logical to arrive at an assumption that the virus can really stay in mesotheliomas for really long, long enough to be found decades later, hence it was found in mesotheliomas decades later, and to be honest if we negate the assumption that i just mentioned, the conclusion breaks completely, i mean if the virus mostly doesn't last long enough to be found decades later, then it might have gotten into mesotheliomas from somewhere other than the contaminated vaccine. Now notice the language of option C, this option is saying that the virus is still very much there in the vaccine, so this does lend us some support to the fact that the virus can last really long, maybe long enough to be found decades later, but does it last long enough to be found decades later in mesotheliomas? we can't say right? just because the virus can last for really long in one environment or ecosystem (the vaccine) doesn't mean that it can last in every ecosystem or environment, including that of mesotheliomas. Hence this option cannot be our answer as it still doesn't really offer any kind of direct support to the hypothesis. Also, this options is merely stating the premise, not really stating but in a way strengthening the premise - "in 1960 some polio vaccine was contaminated with the virus".

option D : totally irrelevant, offers nothing in terms of supporting the hypothesis.


option E : The same polio vaccine was not contaminated in Finland, so sample of mesotheliomas do not contain sv40.

if A --> B, how do we strengthen the mentioned causality? no A --> no B. right?

so no contamination of the same vaccine in Finland, none of the samples of mesotheliomas contains sv40, this means contamination of the same vaccine must have been the cause/source pf sv40 found in mesotheliomas decades later.

option E is the answer.

Researchers’ argument

Premises

1) infection by the SV40 virus is a contributing cause of mesotheliomas, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40.
2) SV40 is a monkey virus
3) however, in 1960 some polio vaccine was contaminated with the virus- SV40


Researcher’s conclusion/hypothesis-

The contaminated polio vaccine was the source of the virus found in mesotheliomas decades later.

We need to find an option that strengthens the Researchers’ conclusion/hypothesis.

Option A- SV40 is widely used as a research tool in cancer laboratories.

This neither strengthens nor weakens the researchers’ conclusion. It is irrelevant. Eliminate

Option B- Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.

The hypothesis is that the contaminated polio vaccine was the source of the virus found in mesotheliomas decades later. Whether the changes in the technique of manufacturing the vaccine now prevent contamination with SV40 or not does not strengthen the hypothesis. Eliminate

Option C- Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

Read the premises again.
3) however, in 1960 some polio vaccine was contaminated with the virus- SV40

We need to find an option that strengthens the hypothesis that the contaminated polio vaccine was the source of the virus found in mesotheliomas decades later. Option C only restates the premise. Eliminate

Option D- In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.

The researchers' hypothesis/conclusion is about mesothelioma and the contaminated polio vaccine, not exposure to asbestos. Eliminate

Option E- In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

Hypothesis- The contaminated polio vaccine was the source of the virus found in mesotheliomas decades later.

Option E supports the hypothesis. In Finland, where the polio vaccine was not contaminated, samples from mesotheliomas do not contain SV40.. This supports the hypothesis that the contaminated polio vaccine was the source of the virus- SV40 found in mesotheliomas. Hence correct.

Vishnupriya
CrackVerbal Prep Team

The passage seems to take a few twists and turns. There are 3 things that are great about this argument:

(1)Identifying the exact Conclusion

As you start reading the passage, it seems as if the Conclusion may be that "researchers believe that infection by the SV40 virus is a contributing cause.... of mesothelioma."

However, by the time you get to the end of the passage, the "hypothesis" that the researchers are putting forth is the following:

"This vaccine [the specific 1960 polio vaccine that was contaminated with the SV40 virus] was the source of the virus found in mesotheliomas decades later."

Supporting this hypothesis made about this casual connection is our goal. We need to find an answer that gives us more belief that:

the Cause ("1960 polio vaccine contaminated with the virus") ----------> leads to Effect ("virus found in mesothelioma tissue decade later")


(2)While it gets trickier the more convoluted the argument gets, it is important to never pick an answer that either appears to Strengthen one of the Premises or explain why one of the Premises occurred.

The Facts in any C.R. argument always have to be taken as definitive.

It becomes difficult to eliminate (C) if you are not able to identify the exact conclusion and its supporting evidence

"Recently discovered samples of the vaccine dating from 1960 still show traces of the virus."

If the crux of the argument was centered around whether or not the polio vaccine contained the SV40 virus, then this answer would provide some support for that argument.

However, we are given as a fact that "in 1960 some polio vaccines were contaminated with the virus." By saying researchers have found MORE samples of the vaccine that still show traces of this virus, all this information does is add on to an existing Fact that we already must take as true.


(3)Finally, one way to Strengthen a Cause and Effect Argument is to somehow show that when the claimed "Cause" is taken way -------> the Effect ALSO DISAPPEARS.

If we take the Cause away and the Effect disappears with it, this gives us a greater belief that the Cause and Effect relationship is as stated by the author.

Again, the main "hypothesis" by the researchers is that this 1960 polio vaccine (contaminated with the virus) is the CAUSE of the virus being found in meso. tissue decades later.

To support this, the author presents the following pieces of evidence:

(1)in 1960 some polio vaccines were contaminated with the virus

and

(2)60% of the meso. tissue samples (but none of the healthy tissue) contained this virus

and

(3) [contained within the conclusion] this virus was found in meso. tissue decades later [after the 1960 vaccines]


One way we can support the hypothesis that the contaminated polio vaccines really were the source and cause of the meso. tissue contamination is to show:

In cases in which the contaminated polio vaccine was NOT present and the vaccine did not have traces of the virus (Cause GONE) ---------->the meso. tissue did NOT contain the virus (Effect GONE)

Answer (E) provides us with such a scenario.

In Finland, the polio vaccines were never contaminated with this SV40 monkey virus (Hypothesized Cause Absent). Furthermore, the meso. samples in Finland were not found to contain the SV40 monkey virus (Effect ALSO Absent).

The answer gives us a little more faith that in America, where the Hypothesized Cause and Effect were found together, it was the contaminated polio vaccine that was the source of the virus found in meso. tissue found decades later.

(E)

Understanding the argument -
The argument is a cause-effect. The researchers hypothesize that "the vaccine" was the cause of the "virus found in mesotheliomas decades later." Why do they hypothesize that? Because in 1960, some polio vaccines were contaminated with the virus. Okay, so how, from that contaminated vaccine, did the virus move to mesothelioma? We don't know. So when I don't know how? At least what I expect is: What if the vaccine had not been contaminated, then I would expect the virus not to have been present in "mesothelioma"? Fair? Yes. "X causes Y" can be bolstered by "not X, not Y." If not X and still Y, then another cause is at play. We need to ensure that there is no other cause.

(A) SV40 is widely used as a research tool in cancer laboratories. - so what? Many things are used in labs, but do they all turn into our bodies? Out of scope.

(B) Changes in the technique of manufacturing the vaccine now prevent contamination with SV40. - Good, but we don't care in our current scope of argument. This is out of scope.

(C) Recently discovered samples of the vaccine dating from 1960 still show traces of the virus. - ok. Confirms the fact we already know. Then what? Maybe some monkey in 1940 bitten someone, and that virus got transferred somehow. First, we already knew this with 100% centrality from the argument as facts are respected on GMAT, and in light of option C, there can still be countable other causes that could have led to the "virus found in mesothelioma."

(D) In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos. - out of scope.

(E) In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40. - ok. Not x, not y, strengthens the x causes y, and no alternate cause exists.