Final answer:
The literary device used when Ursula suggests a "swap" of souls is a metaphor, which directly compares two unlike things without using the words "like" or "as".
Step-by-step explanation:
In the context of the passage where Ursula suggests a "swap" of souls, the literary device used is a metaphor. A metaphor is a figure of speech that makes a direct comparison between two unlike things without using "like" or "as". An example of a metaphor is "Hope is the thing with feathers" by Emily Dickinson. In contrast, a simile would use "like" or "as" to make the comparison, such as, "something inside me / rising explosive as my parakeet bursting / from its cage" by Bruce Snider. Ursula's suggestion does not employ these words; hence, it is not a simile. It is also not an example of hyperbole, which would involve exaggeration, or irony, which typically indicates a disconnect between expectation and reality. Instead, Ursula's "swap" of souls metaphorically proposes a deep and intimate exchange, equating it with a trade of an innermost part of one's being, which cannot literally happen.