Some literary theorists argue that since literary works are expressions of ideology, it is naive to view them as embodying a distinct aesthetic value to a greater or lesser degree.
Conclusion
These theorists succumb to the view they wish to undermine. (they are viewing literary works as embodying a distinct aesthetic value to a greater/lesser degree)
Evidence
They're evaluating particular literary works as being ideological expressions that interesting and successful to a greater/lesser degree)
Evaluate
The "but" shows the pivot from Background/Counterpoint into the Author's argument. The "therefore" shows us that the final sentence is the conclusion, so the second to last sentence was the evidence.
The question stem is asking us about that second to last sentence.
Goal
We're just choosing between Main Conclusion, Supporting, Opposing, Neutral.
Since this 2nd to last sentence was the Premise, we'll look for some answer that sounds like "Supports the Conclusion". However, since this argument is a rebuttal style argument, we could also hear an answer like "evidence that the theorists are dumb-dumbs".