Notice that there are a couple of different prices. The conclusion of the argument is that retail price of cotton clothing will fall. To support the conclusion, the arguer uses an analogy between wholesale price of raw cotton and wholesale price of raw wool, to predict that former will fall. (A) best weakens the argument by pointing out that even if such analogy is appropriate, the cost of processing raw cotton for cloth has increased, contributing to higher total cost for retail price of cotton clothing. As OG points out, even if cost of harvesting raw cotton has increased (note: E does not say "for cloth" -- please check the OG), the most we can conclude is that wholesale price of cotton will increase. This contradicts a more fundamental assumption of the whole argument (the analogy), so is not the correct answer. In my opinion, if A were not a choice, E could also serve as an answer, but A is closer to the argument than E is. | 
