This is the fun but unusual question type where the LSAT asks us to be a bit formal in our logical analysis and actually say what role a particular portion of the text plays in the overall argument. As a general rule of thumb, I am wary of answers that are overly complicated or hard to understand - I only pick these if all of the other answers are definitely wrong.
Also, I find it helpful to find the conclusion and then relate the statement they are asking about to the conclusion - specifically does it help or hurt the conclusion, or is it the conclusion. Let's try to do this here.
Conclusion: It would be too simple to let market forces determine what shows on television.
The claim that tv is important politically and culturally tends to support the author's conclusion. With that in mind, let's check out our options.
(A) doesn't work - this wouldn't describe something that is in sync with the conclusion.
(B) is the opposite of what we want - it's offered against the market forces idea, not for it.
(C) is the opposite of what we want - it's offered in opposition to the idea that market forces alone should determine the content on television.
(D) is the answer. We know already that this statement supports the ultimate conclusion, which this answer choice affirms. There is a lot more going on, but in a fast sweep let's just keep it for now and look at (E).
(E) seems backwards. The idea that something is important does not support the idea that it is used often. Rather it's the opposite - when something is used often it is important. So this is probably not the answer, but it should give you some insight into why (D) is the answer.
If this were the real LSAT, I'd probably cross out (E) and pick (D) without thinking about it anymore. After all, this is a very time pressured test. But let's take a second to go back and look at the rest of the jumble of answer (D).
Let's think about why this is an intermediate conclusion. It's because something being important is not clearly a premise - it would seem to require additional proof to show that something is important. That is precisely the role the other facts in the second part of the argument play overall - they make this intermediate conclusion feasible, which in turn holds up the author's ultimate conclusion.
This is a tough problem and worth thinking about a little extra. Does anyone have any questions or other comments to make about the problem? I'd love to hear what you all are thinking!
#officialexplanation