According to the passage, which one of the following is true of early nonfiction films?

Hello, I am wondering if someone can further explain this and help me not make the same mistake in the future! I wanted to pick D at first because the idea that nonfiction films were supporting attractions was mentioned but I thought that that was in reference to the order in which they are presented, not the films themselves. When I go back and look at the line reference I keep coming to the same conclusion that this answer can be drawn about nonfiction films in reference to where they are presented in a showing but not to the nonfiction films themselves. Where did I go wrong? Thanks for the help!