by giladedelman Thu Aug 26, 2010 9:47 pm
Thanks for the question!
Before we discuss the difference between (B) and (D), let's break down the argument. The conclusion is that an underground band's record sales are not a mark of their success as an underground group. What is this conclusion based on? Two things: on the one hand, if the band sells a lot of records, it may be because they're not really underground enough. On the other hand, if they don't sell a lot, it may just be because they're incompetent.
So what is the critic assuming? Well, in the first case, he's assuming that if a band isn't authentically underground, then it's not successful as an underground band, even if it sells a lot of records. In the second case, the assumption is that an incompetent underground band can't be considered successful, either.
Answer (B) expresses those assumptions. If an underground band is inauthentic or incompetent or both, it's unsuccessful as an underground group.
So why is (D) incorrect? Because the critic never tells us how to judge whether an underground band is successful. If the band doesn't sell a lot of records and is incompetent, it's unsuccessful. But that doesn't mean that a competent band is successful -- the critic never says!
(A) is out of scope. The critic doesn't talk about how well a successful underground group's records will actually sell.
(C) is too broad in scope. We know this is true about one specific criterion, namely, not selling a lot of records, but we can't extrapolate that to criteria in general.
(E) is out of scope. If anything, it seems to be the opposite of what the critic is saying, but we can't be sure. All we know is that incompetence and inauthenticity preclude success as an underground group.
Does that clear this one up for you?