Lady Macbeth’s intent can also be interpreted as her believing that her husband’s weakness will harm his ability to rule. By urging him not to dwell on the murder and to move on, she is concerned that any hesitation or moral anguish will make him unfit to seize the power they desire. This interpretation aligns with her characterization in the play as someone who is focused on ambition and the ruthless pursuit of power, and she fears that Macbeth's guilt could undermine their plans. Therefore, the most fitting response is:
She believes that her husband’s weakness will harm his ability to rule.