Final answer:
In Macbeth, the witches show Macbeth a line of men who resemble Banquo, causing him to become fearful of the witches' prophecies.
Step-by-step explanation:
In the play Macbeth, the witches show Macbeth a line of men who resemble Banquo. This happens during Act 4, Scene 1, when Macbeth seeks out the witches for more information. The witches' prophecies had previously indicated that Banquo's descendants would become kings, and Macbeth becomes fearful of this potential threat to his reign. Therefore, the sight of the men who look like Banquo unsettles him.