Piggybacking off of EducationAisle's (excellent) point, I think that if you were to take "media" as singular, you'd probably lean toward choice E...but even at that, look at the choice itself:

E. In their analysis of campaign expenditures, the media has been focusing on

E isn't even consistent with itself, using the plural "their" with the singular "has been", so again there's a context clue that signals that you don't really need to know plural/singular for "media" if you can analyze the information given to you.