Your thesis statement for Paper 3 needs to be about the American dream
as it relates to The Great Gatsby.
It is true that within the paper you will be writing about how Jay
Gatsby compares and contrasts with Charles Foster Kane from the film
Citizen Kane, but that is a component of an overall paper about the
dream and the novel.
Therefore, you will want something about Gatsby and the dream in the
thesis, but not Kane.
Make the thesis one sentence long. It will be the first sentence of Paper 3.