Political opinion and analysis outside the mainstream rarely are found

E is a good example of a typical trap answer, in that it seems to answer the question but does not really.

Notice what E actually says.

"the television talk shows of different stations resemble one another in most respects."

Does this really have to be true in order for the argument to work?

The author is saying that the opinions offered by television shows are in the "mainstream" and "innocuous".

However, there are to television shows many aspects other than the opinions discussed, aspects such as format, topic, and length. All of these could be different, even if the opinions offered were the same. So the shows could be different in many respects even if they were to offer the same types of opinions.

Further, the author is STATING AS FACT that the shows are bland. So the author is NOT ASSUMING anything about the content or the similarity of the shows. Rather the author is assuming things about THE REASONS for the shows' being bland and innocuous.

Now let's consider B.

"there are television viewers who might refuse to watch television talk shows that they knew would be controversial and disturbing."

To tell the truth, this question is not that tightly written. Does B really fill a gap? Perhaps.

Since none of the other answer choices work at all, let's discuss how B in a way fills a gap.

The authors conclusion is, basically, that the stations offer only bland and innocuous content in order to appeal to large numbers of people. The premise is that stations are driven by economic forces to appeal to large audiences.

There is a gap between the idea the the stations want to appeal to large audiences and the idea that therefore they offer bland and innocuous content. The author seems to be assuming that large numbers of people want bland and innocuous content.

Hence B.