C. It lets the reader encounter the narrator's feeling of triumph in thinking she has freed herself from the wallpaper.
The use of first-person point of view in "The Yellow Wallpaper" allows readers to connect deeply with the narrator's mental state and her transformative experience at the end of the story. This perspective immerses readers in her thoughts and emotions, highlighting her perceived triumph and sense of freedom as she believes she has liberated herself from the constraints of the wallpaper.