Final answer:
King Duncan says the Thane of Cawdor will be executed for betraying them, and Macbeth will inherit the title.
Step-by-step explanation:
King Duncan says the Thane of Cawdor will be executed because he has deceived them by not being loyal and betraying them. In Act 1, Scene 2, Duncan declares that the Thane of Cawdor's title will be given to Macbeth as a reward for his loyalty and bravery in battle.