Millions of homes are now using low–energy lighting, but millions more have still to make the switch, a fact that the...

Emil-Kunkin on March 13 at 09:47PM

We are looking to eliminate four answer choices that would provide information that would be useful to strengthen or weaken the argument. Before we can do that we should think a bit about how the argument is flawed.

While the argument says there are huge benefits to using low watt bulbs, this doesn't guarantee that everyone should use them. We need to know if those benefits outweigh the downsides of the low watt bulbs. So I would expect the four wrong answers to get to the relative benefits and weaknesses of the new bulbs.

A does so directly, as the price differential is a major factor.
C does so similarly to A, although it uses purchase price rather than operating cost.
D does so by questioning the actual value that users place on the bulbs. While the author claims that there are immense benefits, if actual users feel differently that would undermine her claim.
E gets to both cost and usefulness.

B doesn't really do anything for us. While profits are a reason for the companies to push the product, if the claims are otherwise true this isn't relevant. This would only be useful for effectively an ad hominem attack.