In "The Yellow Wallpaper" by Charlotte Perkins Gilman, the line that best demonstrates the unreliability of the narrator is:
C. I can see a strange, provoking, formless sort of figure, that seems to skulk about behind that silly and conspicuous front design.
This line shows the narrator's descent into madness and hallucinations, indicating her unreliable perspective. It suggests that she is seeing things that are not actually there, which calls into question the accuracy of her narration throughout the story.
Another line that highlights the narrator's unreliability is:
A. John laughs at me, of course, but one expects that in marriage.
This line implies a dismissive attitude towards the narrator's concerns and feelings, showing that the narrator's perception of her husband's behavior may not be entirely accurate or trustworthy.
These lines reveal the subtle ways in which the narrator's mental state impacts her interpretation of events, making her narrative unreliable and open to interpretation.