This is a pretty simple question but that doesn't mean there isn't something to learn from it. This is a necessary assumption question so let's find the core!
Plan to ascribe ratings to programs in regards to their levels of violence
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This remedy will forewarn parents about the level of violence
There a few things to note about this question:
1) Notice how the stem is asking you about what the television station must assume. In order to make this easier on your life, shorten the conclusion to just "this remedy would..." If you don't, you may get tongue-tied with ideas of belief, something completely irrelevant
2) Notice how we are talking about levels of violence. This could mean that all programs are not violent, extremely violent, are varied, etc. We know nothing about the programs themselves and it is perfectly okay - we don't have to know anything because we will stick to the core.
3) The gap here is simple: the argument is assuming that parents will actually read the newspapers themselves and receive its pertinent information.
With all of this in mind, let's jump right to it!
(A) is pretty much exactly what we wanted. If they wouldn't read the newspapers, then how would they get the information and be "forewarned?" This is correct.
(B) is the trap! Look at 2) above and you'll see why this is wrong right away. The nature of the shows don't matter one bit! They could all be incredibly non-violent or they could all be completely violent. It doesn't matter.
(C) is a very common wrong answer. This particular system doesn't necessarily have to be the "most effective." It has to be effective to a point, only effective enough that parents are actually forewarned but it doesn't have to be the most effective. It could still forewarn parents without necessarily having to be the most effective.
(D) is talking about "obligation," something that we really don't care about. Obligation is not only never mentioned in the stimulus but it has no bearing on the argument! So they have an obligation; they don't have an obligation; they like giraffes; none of this matters!
(E) No effort to reduce the levels is necessary. Similar to (B), this gets into the nature of the shows themselves. We don't care about that because we care about the process of forewarning parents.