Final answer:
Macbeth responds with curiosity and a desire to learn more about Banquo's dream and the witches' prophecies.
Step-by-step explanation:
When Banquo tells Macbeth about his dream of the three weird sisters, Macbeth responds with curiosity and a desire to learn more. He asks Banquo to tell him more about what the witches said and where they received their information. Macbeth is intrigued by the witches' prophetic greetings and is open to the possibility of becoming king, even if it happens by chance. He also questions Banquo about the reality of the witches' prophecies and wonders if they may have eaten something that has affected their reasoning.