Answer: A. She thinks that the wallpaper is having the same effect on them as it is on her.
The story describes a woman who spends most of her time staring at the yellow wallpaper of her room, as she has no other significant stimulation. She was placed there because her husband believed rest to be a good treatment for her depression. With little else to look at, she becomes intrigued and later obsessed with the wallpaper's pattern, missing patches, and other unimportant details. In this excerpt, the woman reveals that she thinks other people are reacting similarly to the wallpaper.