4. (E)
Question Type: Identify the Flaw
The author concludes that the posters are unlikely to boost employees’ motivation. The reasoning used to make this conclusion is that these employees are already motivated. If we read critically, we can anticipate the flaw in this argument. The argument assumes that someone who is already motivated can’t become even more motivated. Answer (E) clearly expresses this flaw.
(A) is incorrect because this is exactly what the argument is considering.
(B) is wrong because it doesn’t matter at all if the corporations in question ("these corporations" as stated in the conclusion of the argument) are representative of corporations in general. The argument is concerned only with the corporations mentioned.
(C) may be true, but it is outside the scope of the argument. The argument pertains to the posters’ effect on motivation. Any other possible effect is irrelevant.
(D) is incorrect for the same reason. Other factors that might contribute to productivity are outside the scope of the argument. We care only about the posters’ impact on motivation.
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