Answer:
B. Pandora's box.
Step-by-step explanation:
Allusions are indirect references to a place, thing, person or an idea with an unrelated context. It is used as a figure of speech. For example, "He seems worse than Brutus", "Your garden looks like the Garden of Eden", "I met a Good Samaritan", "Such a Herculean task!".
Here, since Harper was a curious a child, her mother has made an allusion to Pandora's box because Pandora, according to the myth, was a curious girl. She had endless curiosity to what was inside the box.