Media producers can target audiences by:
a. showing things that are positive.
b. using bias.
c. creating media that appeal to their audience.
d. telling every side of most stories.

Probably the correct answer is C. Because if they want to target audiences, of course they are going to create media that will appeal to them. Whether they show "things that are positive", "use bias", or "tell every side of most stories" is irrelevant, because they need to create something that will attract their audience, regardless of the content. 

The answer would be c.