E is incorrect because this option focusses on the relation between the price and sales of phones. This relation is not explored/mentioned in the argument. Thus, if falls out of scope.
Hope it helps.
PS: Please get this thread moved to appropriate section.
Nothing is wrong with the last option, matter of fact (E) should be the answer here. (A) on the other hand is wrong because it talks about the decline in the company's share - The stimulus does not tell us anything about the company's share. We are only concerned with the sales of the phone.