Final answer:
Lady Macbeth utters the line regarding the Thane of Fife's wife in the sleepwalking scene, revealing her deep-seated guilt and fears.
Step-by-step explanation:
The line "The thane of Fife had a wife; where is she now?" is uttered by Lady Macbeth in Shakespeare's play "Macbeth." This line can be found in Act 5, Scene 1, which is known as the sleepwalking scene. During this scene, Lady Macbeth is sleepwalking and reveals her guilt and fear about the murders that she has been a part of. It reflects her distraught mental state and her obsession with the death of Lady Macduff, the wife of the Thane of Fife. This haunting question encapsulates her harrowing descent into madness, illustrating the overwhelming weight of culpability and the visceral repercussions of their bloody ambitions, exposing the grim toll exacted by their treacherous path.