Answer: C. Allusion.
Step-by-step explanation: Allusion is a literary device that consists in making a brief reference about an event, it can be historical, political or cultural, it also can be a reference to a person or a place. When Maggie came across a reference to Cleopatra, the famous Egyptian queen, she should realize that the poet is using the literary device of allusion (in this case to a person), so the correct answer is option C.