Answer:
3rd option has the same meaning as the given sentence.
The setting builds atmosphere to whether the environment in the story is pleasant or disturbing, it can build a sense of uneasiness if the author describes darkness and destruction in the story . Likewise , if a setting is full of light and flowers , it implies a happy and pleasant mood.
This fact that this passage is from the perspective of an unreliable narrator is supported by the fact that nobody believes the narrator and at times she barely believes herself.
When she asks Agnes, it is clear that Agnes believes the narrator was dreaming or is lying. The narrator then second guesses herself and tries to justify the vision she saw as some friend of the servants. She decides not to ask anyone else (in case they also think she is making it up), which leads the reader to think that she might not be entirely reliable.