Hmm. I'll try negating (B)and (C). (B): Nighttime News content is not more closely aligned with audience than World News content. Maybe they're about the same? That doesn't really hurt the author's argument all that much. (C): None of the World News viewers liked Nighttime News better, why would they switch? Negating this definitely hurts the argument. So Choice (C) must be necessary. Choice (C) it is!