Final answer:
In Act III, Macbeth reacts with shock and fear to the ghost of Banquo, speaking directly to it and displaying agitated behavior.
Step-by-step explanation:
In Act III of Macbeth, Macbeth's reaction to seeing the ghost is one of shock and fear. When the ghost of Banquo appears at the banquet, Macbeth responds in a way that draws the attention of his guests. He does not calmly address the ghost or dismiss it, nor does he confess to his crimes or act normal to pretend the ghost is not there. Instead, Macbeth becomes agitated and speaks to the unseen ghost, causing concern and confusion among the attendees. His behavior escalates to the point where Lady Macbeth has to intervene.
Macbeth's initial reaction is captured as he says:
"Which of you have done this?" (Lines 48-49)
And further:
"Thou canst not say I did it: never shake Thy gory locks at me." (Lines 50-51)
As Macbeth communicates with the ghost, his fear and bewilderment become evident, illustrating the toll of his guilt and the beginning of his mental unraveling.