The correct answer is: C."Or art thou but / A dagger of the mind".
This option best demonstrates that the dagger Macbeth sees is an illusion, because Macbeth states that dagger he sees is possibly "a dagger of the mind". Macbeth is a famous play written by William Shakespeare. The plot of the play involves a Scottish general, called Macbeth, who believes a prophecy, and kills King Duncan, in order to replace King Duncan as the King of Scotland. After Macbeth kills the King, he experiences guilt and unrest, which in turn leads to him experiencing hallucinations. Thus, Macbeth sees daggers that are imaginary, as he experiences hallucinations.
