Answer:
D) It raises the stakes and ratchets up the tension in the story as the narrator wonders what is in the box.
Explanation:
The protagonist narrates the story in such a manner it makes the reader think Aunt Gertrude's secret is most likely a terrible one. This element of story-telling helps building up suspense before reaching the climax of the story, although in the end the reader realizes the true nature of Gertrude's secret and how it is not so terrible as it was built-up to be.