The correct answer is a.Banquo has noble qualities that make him worthy of being a king.
In Act lll, scene l, in his monologue Macbeth declares that being a king means nothing unless he can be safe and secure in his new role. He also acknowledges he has a deep fear for Banquo for the following reasons:
- Banquo has noble qualities and is good, turning him into a powerful adversary.
- Banquo is strong-willed and corageous, willing to take risks for the sake of good.
- Macbeth has a feeling that Banquo could unveil his plot to kill Duncan.
It also noteworthy that Macbeth also feared Banquo due to the development of his prediction made by the witch sisters.