I found myself begrudgingly spending way too much time on this question than I would have liked too, and as a added bonus I choose C, an incorrect answer!
The reasoning behind it was that public interest needs to be considered, because it compromises many interests and must serve all of them. Considering only one aspect of it, say those that like action shows, would result in a problem, but a broader concern with public interest could help to negate this problem. To say the least, I was disappointed when I saw that this was the wrong choice.
I know I should probably give them some flexibility with the term "popularity", but it seems like something can be popular with 5% of the market, and that this could be a segment that is represented by the broadcaster's.
As I read it now, I see that C has the word "should" in it. This seems a bit prescriptive, but I wonder whether or not it is warranted because the first sentence states that something "must" be the case.
tl;dr, why is A right, why is C wrong?