Answer:
C. Come, let me clutch thee.
Step-by-step explanation:
The evidence that leads readers to believe that the dagger Macbeth sees is an illusion is option C Come, let me clutch thee.
These events occurred in the Act 2, Scene 1 of Macbeth when Macbeth was soliloquizing. At that part of the play, he was ready to murder Duncan and as a result of this, he kind of loses his nerve and starts to wish that he didn't have to kill Duncan.
Duncan sees an illusion of a dagger before him because he sees the handle of a dagger but it turns out to be a product of his mind because he says that it is a "fatal vision".
Therefore, option C is the correct answer.