The correct answer is 4. Krapp’s Last Tape because it is a play by Samuel Beckett that features a single character, Krapp, who primarily interacts with himself and recorded versions of his voice. This structure is a hallmark of Beckett's minimalist and introspective style.
Here's why:
Krapp’s Last Tape: The play revolves around Krapp, an aging man, who listens to old recordings of himself reflecting on his past and records new reflections. Most of the dialogue is either Krapp speaking to himself or the recorded voice of his younger self. This exclusivity of a single character's monologue, coupled with his introspection and interaction with his own recordings, makes it the correct choice.
Why not the others?
A Streetcar Named Desire: This play by Tennessee Williams involves multiple characters, such as Blanche, Stanley, and Stella, interacting in a complex narrative. It is not characterized by a single character speaking to themselves.
Equus: Written by Peter Shaffer, this play features multiple characters and dialogues, especially between the psychiatrist Dysart and the troubled boy Alan Strang.
The Misanthrope: Molière's play is a comedy of manners involving several characters and their interactions within society, not focused on a single character's monologue.
Thus, Krapp’s Last Tape is unique among the options as it is centered on a solitary figure speaking to himself, either directly or through his recordings.