Unlike the wholesale price of raw wool, the wholesale price of raw cot

IMO A.

You need to check carefully the terms marked in red. Stimulus says that the prices of RAW WOOL decreasing, prices of COTTON CLOTHING has not fallen but will inevitably fall. This is the conclusion. We have to find an answer which weakens this conclusion.

If there is some factor, which can counter balance the decreased prices of raw cotton with increased prices of cotton clothing, will be correct answer. Let's check all options:

A. The cost of processing raw cotton for cloth has increased during the last Year. [Bingo, now thats what I am talking about. Wait lets check other options as well]
B. The wholesale price is typically higher than that of the same volume of raw cotton. [So what? How does it affect the clothing rate. Incorrect]
C. The operating costs of the average retail cloting store have remained constant during the last year. [We are discussing the relationship b/w pricing of raw cotton and cotton clothing. This choice is irrelenet to our concern. Incorrect]
D. Changes in retail prices always lag behind changes in wholesale prices. [Oh really. What if there is less harvest of raw cotton and no overstock for manufacturers? Incorrect]
E. The cost of harvesting raw cotton has increased in the last year. [This is strengthing the conclusion. Beware it is an example of OPPOSITE case fallacy.Incorrect]

So, A is the best answer.

A it is as it connects the link between wholesale price of raw cotton and the processing price of raw cotton into cloth.

E talks about harvesting raw cotton: An event, information or premise that could have affected the wholesale prices of cotton itself. But, it is clearly mentioned in the passage that wholesale price of the cotton dropped. So, even if E is correct, we can safely assume that it has nothing to do with the retail price increase. There may be something else that could have caused the wholesale prices to drop in spite of higher harvesting cost but we should not be bothered about that.

A: Correctly gives an alternate reason why the retail price may not fall. Because, although the wholesale prices have fallen, the cost of processing them into clothing has risen. Thus, the cotton clothing manufacturers will have to sell the clothes at the same price as they did before and eventually the retailers will have to sell it at the same rate as before as well.

It is important to note that these options just give a reason to suspect the argument. It doesn't completely disapprove the argument.

For this question I picked A:

From reading this passage, I immediately picked out the conclusion to be [highlight]"Thus, the price of cotton clothing will inevitably fall."[/highlight] If you are having trouble finding the conclusion, look for the conclusion marker "thus" and it should be easy from there.

The question stem then tells you that you are looking for an answer choice that weakens the argument.

The next step I took was to prephrase because this could potentially direct me to the correct answer and prephrasing forces me to think harder about what I just read.

So how did I prephrase this question? If you look back at the passage, you are essentially given a direct relationship between the price of raw cotton and the price of cotton clothing. This relationship makes sense if you ASSUME that the processing/manufacturing from raw material to finished product has not changed in cost. Therefore, my first prephrase was: [highlight]An increase in manufacturing/processing costs.[/highlight] This would definitely weaken the argument because an increase in manufacturing costs would decrease the retailer's profit margins and may force the retailer's to leave their prices constant.

What is another possible prephrase? Well, it is possible that the retailer's themselves may have higher operating costs (ie. rent, electricity etc.) which would again squeeze the profit margins of the retailers. [highlight]Therefore, my second prephrase was: Increased operating costs of the retailers.[/highlight]

Now we can analyze each and every answer choice:

A. This answer choice matches one of my prephrases (My prephrase looks suspiciously similar to the answer choice, but I'm honestly telling you that I did not look at the answer choices until after my prephrasing. This should tell you the importance of doing this.) This is a definite contender and after looking at the other choices, I have determined that this is the correct answer.

B. The relationship in the passage is between price of raw cotton and the price of cotton clothing - the relationship between the price of raw wool and the price of raw cotton is irrelevant.

C. This answer choice is incorrect because it states that the operating costs have remained CONSTANT. If this answer choice had said that the operating costs have increased, then this answer choice would definitely weaken the argument, but as it stands, this answer choice actually strengthens. The reason it strengthens is because it eliminates one of the reasons that could explain the error in the initial relationship.

D. This answer would be correct in a must be true question - it just summarizes what is already stated in the passage. Therefore, if anything, this answer choice strengthens.

E. The cost of harvesting should already be included in the wholesale price of raw cotton, therefore, this answer choice is irrelevant.

Question type: Cause & Effect.

Back to the ques:
Cause: wholesale price of raw cotton has fallen
Effect: price of cotton clothing at retail clothing stores will fall.

Pre-thinking: Retail cloth price will not fall because some cost in between will compensate the price fall of wholesale cotton.

A. The cost of processing raw cotton for cloth has increased during the last Year. - same as pre-thinking. Raw cotton is cheap but processing charge is high, so end product cost will remain same.

B. The wholesale price is typically higher than that of the same volume of raw cotton. - This is extra information regarding the wholesale price,but do not address the relationship between wholesale price and retail price.

C. The operating costs of the average retail clothing store have remained constant during the last year. We are not concerned about the price of electricity bill, water bill or staff salary of the store.

D. Changes in retail prices always lag behind changes in wholesale prices. - This is not a weakener, this is talking about the usual trend, which may happen.

E. The cost of harvesting raw cotton has increased in the last year. - purely a strengthener.

Conclusion :- Retail price of cotton clothing at retail clothing stores will fall.
Weaken :- Retail price of cotton clothing at retail clothing stores will not fall.

To make this argument very basic:
Premise: The price of raw cotton has fallen.
Conclusion: The cost of cotton clothing will fall.

What is the author assuming? That the cost of cotton clothing is ONLY influenced by the price of raw cotton. That seems like a weak assumption, since many other costs could go into the conversion of raw cotton into cotton clothing.

To weaken the argument, attack the assumption that only the cost of raw cotton influences the price of cotton clothing. (A) does this nicely, illustrating that there are other possible factors that go into the final cost of cotton clothing, such as the cost of processing the cotton.Also, Option A: Correctly gives an alternate reason why the retail price may not fall. Because, although the wholesale prices have fallen, the cost of processing them into clothing has risen. Thus, the cotton clothing manufacturers will have to sell the clothes at the same price as they did before and eventually the retailers will have to sell it at the same rate as before as well.
Thus, A is best choice here.

This is such a great question, simple yet tricky - I landed at A and E. Between A and E after much thought I marked A. I think for weaken questions we must focus on the conclusion and make sure that the option we choose ties into the argument and weakens it.

I was tempted to choose E as well with some reading precision and the word cloth I ended up choosing A.

Wow GMAT!­

GMATNinja. please tell my reasoning for option C is correct or not. As we know operating cost for shop is constant and there is no further information about how whole prices are going to effect retail prices. This option is not going to affect the argument . For weakening or strengthening we have to make unreasonable assumptions. 
thanks­