What does this except from the end of yellow wallpaper tell the reader about?

B) The narrator believes that she was once behind the wallpaper herself.

Explanation:

In the given excerpt from "The Yellow Wallpaper" we can see the description of how the narrator doesn't like to look out of the windows because she sees creeping women. From the given options, the phrase that tells the reader about the narrator's mental shift is "The narrator believes that she was once behind the wallpaper herself" we can see this when she says " I wonder if they all come out of that wall-paper, as I did?"