Secondary characters would most likely be used in a subplot.
C should be the answer. A doesn't help you organize information, because it's "random" labeling. B includes paragraphs, which you usually don't construct in an outline bc outlines are brief. for D, it's a research paper and one can assume that all information is fairly relevant and important, plus color coding isn't a typical part of an outline. E says to list it alphabetically but that doesn't help you organize your information either because you don't necessarily want your research papers to be alphabetical, you want them to follow a logical path.
