The proposed coal-burning electric plant should be approved,

EXPLANATION FROM POWER SCORE

This argument concludes that the plant should be approved because those opposed to it presumably have a stake in its rejection:

Premise: All arguments against the plant have been presented by competing electricity producers;

Premise/Sub conclusion: No good arguments have been offered against it;

Main conclusion: The proposed plant should be approved.

This line of reasoning is not sound. Even if all the arguments against the plant are presented by competing electricity producers, this does not automatically mean that these arguments are bad. This is a flaw in the reasoning called "source argument" (or ad hominem attack). An argument can still be good even if its proponent has a vested interest in it. Second, even if no good arguments have been offered against the plant, their absence does not amount to an argument in its favor.

Because this is an Assumption question with a rather weak stimulus, you should look for a Defender Assumption that overcomes one of its weaknesses. For instance, it is essential to the author's conclusion that at least some of the arguments made by those who have a vested interest in the failure of the plant be bad. It is also necessary that the absence of a good argument against the plant amounts to a definitive argument in its favor.

Answer choice (A): This answer choice strengthens the argument by implying that the competing electricity producers have a particularly strong interest in seeing the proposal fail. However, the author's conclusion does not rely on the particular nature of such interests: she only needs to establish that they have a negative impact on the strength of the producers' arguments. Try the Assumption Negation technique: what if the producers do not stand to lose large amounts of money? They can still have a vested interest in seeing the project fail, and their arguments can still be defective. This answer choice is incorrect.

Answer choice (B): This answer is the Mistaken Reversal of what we need. Instead of establishing that the competing electricity producers' arguments against the proposal are defective, it presumes that they are. If the sufficient and necessary conditions in this answer choice had been reversed, this would have been a great Defender Assumption.

Answer choice (C): The net positive effect of the plant's approval on the energy industry's overall level of happiness might be an argument in favor of building the plant, but it is not essential to the author's conclusion. Even if disapproval pleased the competitors more than approval pleased he supplies, the argument would still hold.

Answer choice (D): Unfortunately, there is no evidence that any good arguments were presented for the proposal, which is why this is not an element essential to the author's conclusion.

Answer choice (E): This is the correct answer choice. By establishing that arguments made by those who have a vested interest in the proposal's failure are not good arguments, this answer choice provides a necessary premise to the author's conclusion. If these arguments were good, on the other hand, her conclusion would no longer be valid.