Which figure of speech involves directly addressing an absent or imaginary person?

The correct choice, which is apostrophe, refers to a figure of speech where a speaker addresses someone who is not present, an imaginary character, or an abstraction as if they were capable of responding. This device is often employed in poetry and rhetoric to evoke emotion or to create a dramatic effect. For example, in a line where a poet addresses death, saying, "O Death, where is thy sting?" the speaker is formulating thoughts directly to an entity that cannot respond, enhancing the intensity of the expression and allowing readers to engage more deeply with the subject matter.

Analogy involves drawing a comparison between two different things to highlight some form of similarity. Anaphora is a rhetorical device that involves the repetition of a word or phrase at the beginning of successive clauses, aimed at creating emphasis. Alterity refers to the concept of 'otherness' and is often discussed in philosophical and sociological contexts, but does not pertain to the direct address of an absent or imaginary person. Thus, apostrophe stands out as the figure of speech that specifically meets the criteria of addressing an absent or imaginary entity.