Construction is causal.
Adverse effects caused -> decrease in coffee consumption.
To weaken find other cause.
C weakens but the best is E, C addresses two different categories, whereas E is very general statement and inline with the argument.

bakhshaliyev wrote:Why not C?

as i get from the period of time studying CR, to weaken an argument we must
1/ find another sentence which directly weaken the conclusion ( a sentence which strengthen the reason why coffee consumption decreases)
2/ find another reason which can explain why coffee consumtion decreases)

so E does that. it gives out another reason by saying that its because of decreasing supply of coffee so ( maybe price is hight) people stop buying coffee for awhile, thus saying that people are decreasing coffee because of taking care for their health is not correct. So it weakens the argument.

in my opinion, C is irrelevant, price is not mentioned. everything we care here is the consumption of coffee and health problems

The answer should be E.

This is a very long post.I tend to over explain! I hope that you read it till the end! I'm positive that all your doubts will be addressed.

I assume that you understood why A,B,and D are incorrect.If you don't I can give you a very detailed explanation for why they are.

Evidence:

Coffee consumption decreased
At the same time,there has been increasing awareness of the adverse long term effects of coffee on health

Conclusion:

Awareness of adverse long term effects -> decrease in consumption.

Can you see the assumption.This is one of the easier questions;There is a huge gap (assumption) that nothing else probably a severe shortage of coffee caused this drop in CONSUMPTION.

Yes it is an assumption :if the coffee crop became extinct,then even if people want coffee they can't consume because coffee is just not available.

Another assumption could coffee just got very expensive [remember oil crisis back in 2008? If I were to tell you that: people became more aware about the environment back in 2008 and that the consumption of oil fell back in 2008.Therefore,this awareness caused this reduction consumption."

Now if someone comes and says "The price of oil doubled in a period of 8 months to the highest level in history"

Can I make the conclusion? No

This is the reason why E is correct.

Now to answer choice C

It says that consumption special types of coffee held steady and the consumption of regular coffee fell.

From evidence I know that the overall consumption of coffee fell.The answer choice in GMAT,as in LSAT,cannot contradict the evidence itself.So you can't say that "the evidence is wrong.The consumption actually rose."This is the main reason why I think that I you chose C.

At best answer choice C gives the breakup of the consumption of the various varieties of coffee available!

So this is irrelevant.

if I assume that this special type of coffee contains lots of caffeine [assuming in a weakener is not allowed].A weakener has to explicitly state that this special coffee contains more caffeine than regular coffee.It weakens the argument;If I assume that this special type of coffee contains much less caffeine than the regular coffee,the conclusion is strengthened.

That is why you should never assume anything.Take everything at face value.This is like D.S in quant.You can't assume anything in a particular statement to make it sufficient.

I hope I addressed your issues.

OG CR questions as well as GMATPrep,infact any official GMAT or LSAT questions,are very crisp;There is never ever an ambiguity in those questions.IF you think there is more than 1 correct answer,think more deeply.You are missing something.There is always a reason for eliminating an answer.

diebeatsthegmat wrote:

bakhshaliyev wrote:Why not C?

as i get from the period of time studying CR, to weaken an argument we must
1/ find another sentence which directly weaken the conclusion ( a sentence which strengthen the reason why coffee consumption decreases)
2/ find another reason which can explain why coffee consumtion decreases)

so E does that. it gives out another reason by saying that its because of decreasing supply of coffee so ( maybe price is hight) people stop buying coffee for awhile, thus saying that people are decreasing coffee because of taking care for their health is not correct. So it weakens the argument.

in my opinion, C is irrelevant, price is not mentioned. everything we care here is the consumption of coffee and health problems

The word sales is different from price.Sales means amount of quantity sold

Sales-oxford dictionary definition

[mass noun] the exchange of a commodity for money; the action of selling something:

we withdrew it from sale

[count noun] :(sales) a quantity or amount sold:

price cuts failed to boost sales

Here the sales is acting as a count noun.

GMAT never introduces ambiguity in the words it uses.Words have very crisp and clear meaning.If it intended to say prices,it would have explicitly stated the word price instead of sale.

Thanks a lot for your explanation