Respuesta :
Four is definitely a choice. The author is drawing a conclusion on what really happens with the use of 19th century fictional writing practices. That conclusion comes entirely from his own background, and his own experience with the literature he has engaged reading and commenting on.
You can't really use 1 and 2 although you could use both if you had the sentence that was after both of them.
So that leaves you only with three. The "enhance the illusion of reality" is a good phrase and fits the criteria that we are supposed to use in answering this question.