At the beginning of Act V, Shakespeare has Lady Macbeth on stage holding a candle and mumbling to herself. What purpose does this scene serve?

A)This is the prologue to Act V and sets up the action that is going to happen.
B)This shows the Doctor and Gentlewoman watching.
C)This is an indicator of Lady Macbeth’s mind.
D)This is a review of the action so far in the play.