Because ethylene dibromide, a chemical used to fumigate grain, was

IMO C

IF ethylene dibromide does not take two years or longer for that damage to become detectable then it is either the new chemical or ethylene dibromide that is causing the damage..

If ethylene dibromide does takes more than 2 years then the conclusion is wrong..Then the only reason for the damage is ethylene dibromide..

Hope that helps..

If u like my post..consider it for kudos

A. If the new chemicals cause nerve damage, the nerve damage caused would be different from any nerve damage that ethylene dibromide may cause. - Nerve damage in general is discussed in the passage rather than the type of nerve damage. Insignificant to the current context - Incorrect
B. There are no chemical fumigants that are completely safe for workers in grain processing plants. - The effect of those fumigant on the workers are being discussed rather than the level of safety - Irrelevant - Incorrect
C. If ethylene dibromide causes nerve damage, it does not take two years or longer for that damage to become detectable. - Assuming that Ethylene dibromide takes two years to cause nerve damage and it takes two years to get detected, then it can be said that Ethylene dibromide is the sole culprit for the nerve damage. Since new cases emerge after changing the fumigants, the new chemical also causes nerve damage - Correct
D. Workers at grain-processing plants typically continue to work there even after being diagnosed with nerve damage. - The passage clearly mentions that new cases of nerve damage have been detected. It has nothing to do with the old workers working at the plant - Incorrect
E. Workers at grain-processing plants that still use ethylene dibromide continue to have a high rate of nerve damage. - Irrelevant information - Out of context - Incorrect

Hello,
Can someone please walk me through with this problem.

Thanks

Sure! I can give this a shot.

Ok, this questions asks for the assumption. Lets find the premises and conclusion first:

Premise 1: Because ethylene dibromide, a chemical used to fumigate grain, was blamed for the high rate of nerve damage suffered by people who work in grain-processing plants, many such plants switched to other chemical fumigants two years ago.

Counter premise: however, the percentage of workers at these plants who were newly diagnosed with nerve damage has not dropped significantly.

Conclusion: Therefore, either ethylene dibromide was wrongly blamed or else the new chemicals also cause nerve damage.

Now, we have to find the assumption on which the conclusion, i.e ethylene bromide was wrongly blamed, is based.
Maybe a diagram will help?

eth bromide---> caused problems
.
.
After 2 yrs
.
.
Switched to another chemical---> problem still exists!

So--> ethyl bromide is NOT the root cause of this problem

Now, lets look at the answer choices: (Remember, we have to focus on the conclusion, i.e ethyl bromide is not the root cause)

A. If the new chemicals cause nerve damage, the nerve damage caused would be different from any nerve damage that ethylene dibromide may cause. Not true because this tells us about the new chemical and a if scenario. But we already know that the new chemical causes nerve damage. Besides this wont help us conclude that eth bromide is NOT a cause for damag

B. There are no chemical fumigants that are completely safe for workers in grain processing plants.
This is too broad to claim that no chemical is safe

C. If ethylene dibromide causes nerve damage, it does not take two years or longer for that damage to become detectable.
If you remember the premise, it says that after 2 yrs workers switched to a new chemical. Which means that it takes less than 2 years to detect the damage caused by ethylene bromine. So this is the correct answer choice
Another way to prove this is the correct answer is to negate it. If we said that it takes MORE than 2 years for ethylene bromine to be detectable, then we cannot prove if it was ethylene bromine or the new chemical that caused the damage, since we already switched to the new chemical within 2 years. So this statement is a good assumption
D. Workers at grain-processing plants typically continue to work there even after being diagnosed with nerve damage.
This would actually weaken the argument because if the workers worked, there is no way of proving which chemical caused the damage
E. Workers at grain-processing plants that still use ethylene dibromide continue to have a high rate of nerve damage.
Not an assumption, because it does not directly support the conclusion which is: ethy bromine is NOT the root cause fot the damage.

Hope this helps.

It looks like someone was faster than me but since I did this on my phone (while watching my son's soccer game 0-0 tie) I'm still to post it

Remember that assumptions fill the gap between premises and the conclusion. Here the premises are 1) that plants switched away from ED TWO years ago because ED was blamed for nerve damage and 2) that the percentage of NEW nerve cases has not dropped. The conclusion says that either ED was not the problem or that the new chemical is just as bad. The assumption will connect these premises to the conclusion and will make the conclusion more valid.

A-The argument does not discuss any difference in types of nerve damage only the percentage of cases - out of scope
B-Completely out of scope
C- In order to conclude that ED was wrongly blamed for NEW cases after the change TWO years ago we have to assume that is doesn't take time for these nerve damages to be detected. - correct
D- out of scope - doesn't help us with the source of nerve damage at this plant
E- again out of scope because we are concerned about nerve damage cases and this plant that no longer uses ED.

KW

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Posted from my mobile device
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The plant changed from one possibly nerve-damaging chemical to another 2 years ago. But the proportion of workers suffering nerve damage has not changed. The argument concludes that the change made no difference. The argument is assuming that 2 years is a long enough time window to judge whether the change was effective - if nerve damage only appears, say, 10 years after exposure to the chemicals, we wouldn't be able to say anything about the change in chemical after only 2 years. That's why C is an assumption here.
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Hi..
Yes , the correct answer is C

Premise : Because ethylene dibromide, a chemical used to fumigate grain, was blamed for the high rate of nerve damage suffered by people who work in grain-processing plants, many such plants switched to other chemical fumigants two years ago. Since then, however, the percentage of workers at these plants who were newly diagnosed with nerve damage has not dropped significantly

Conclusion : Therefore, either ethylene dibromide was wrongly blamed or else the new chemicals also cause nerve damage.

A. If the new chemicals cause nerve damage, the nerve damage caused would be different from any nerve damage that ethylene dibromide may cause.
it weakens the conclusion by adding new information that new chemicals will cause different kind of nerve damage than ethylene dibromide. Opposite answer

B. There are no chemical fumigants that are completely safe for workers in grainprocessing plants.
Not relevant

C. If ethylene dibromide causes nerve damage; it does not take two years or longer for that damage to become detectable.
It correctly state the assumption that if negated will weaken the conclusion. Lets say if ethylene dibromide caused nerve damage can be detected after two years the person got infected then the current nerve damage cases could be because of that and then conclusion that dibromide was wrongly blamed will be wrong. So to fill the gap between premise and conclusion and to support the conclusion this statement has to be true

D. Workers at grain-processing plants typically continue to work there even after being diagnosed with nerve damage.
Out of scope

E. Workers at grain-processing plants that still use ethylene dibromide continue to have a high rate of nerve damage.
Out of scope

HI mira93, nightblade354, eakabuah

Please add the tag as GMATPrep
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Done. Thank you.
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Need to focus on not only conclusion but also its premise to understand completely.

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