The line “Thou still unravished bride of quietness” presents
which of the following rhetorical figures?

The correct option is Apostrophe.

In literature, an apostrophe is a rhetorical figure of speech in which a speaker directly addresses an absent or dead person, an abstract concept, or an inanimate object as if it were present, alive, and capable of understanding.
In the given line, which is the opening line of John Keats's famous poem Ode on a Grecian Urn, the speaker is directly addressing the physical Grecian urn itself, calling it the “Thou still unravished bride of quietness.” Since an urn is an inanimate object that cannot hear or respond, addressing it directly using the pronoun “Thou” is a classic example of an apostrophe.

To understand why the other options are incorrect, let us look at their definitions:
1. Anastrophe refers to the inversion of the usual word order in a sentence (e.g., placing the adjective after the noun).
2. Anaphora is the repetition of a word or phrase at the beginning of successive clauses or sentences.
3. Chiasmus is a rhetorical device in which words, grammatical constructions, or concepts are repeated in reverse order (e.g., "Ask not what your country can do for you; ask what you can do for your country").