Final answer:
In Act III of The Tragedy of Macbeth, Macbeth has become more likely to use treachery to achieve his goals.
Step-by-step explanation:
In The Tragedy of Macbeth, Act III, Macbeth has most clearly changed by becoming more likely to use treachery to suit his ends. This is evident in his decision to have Banquo murdered and in his plan to have Macduff's family killed. Macbeth's increasing willingness to resort to violence and deceit shows a significant shift in his character from the beginning of the play.
Learn more about Macbeth's character development throughout the play