The public is aware of the possibility of biases in the mass media and

In this question we know the answers are all conclusions and in any good GMAT question a good conclusion will be drawn only from information in the argument. So I think the best approach is to go through A-E and check that the info contained in each answer is correct.
A – Correct – The argument is saying that the public get their information from the media which makes up their sense of normality. Therefore if there is a trend in that information (i.e. a persuasive bias), that would appear normal. The first sentence confuses us because it says people don’t trust the media which insinuates that we are consciously aware of it. But thats not the case, we suspect it because of we see the media as too powerful (and are therefore aware of the possibility of bias), but crucially we don’t know there is bias.
B – No mention of politics, easy elimination
C – No mention of how this bias is skewed, eliminate.
D – There is no mention in the argument about the ‘values’ of new reporters, news programs or even the media in general, only about the presence of bias. Eliminate
E – Out of scope as the argument talks about how the public perceives the media, not what would happen in an event which is contrary to what we expect.