Final answer:
The rhetorical device used in the sentence is chiasmus, which is the mirroring of grammatical structures to emphasize a point.
Step-by-step explanation:
The rhetorical device used in the sentence "you can take the girl out of the country, but you can't take the country out of the girl" is chiasmus. Chiasmus is the use of reverse grammatical structures in successive phrases or clauses for rhetorical effect, creating a mirror-like structure. This sentence reflects the reversed concepts of being taken from the country and the country residing within the person, which distinctly exemplifies this rhetorical device by juxtaposing the two parts against each other to make a point about inherent identity versus external environment.