Which of these lines provides important information for the exposition of the play? O Banquo, Banquo!/Our royal master's murder'd! And, for an earnest of a greater honor,/He bade me, from him, call thee Thane of Cawdor Thou know'st that Banquo, and his Fleance, lives. Hail, king, for so thou art: behold, where stands/The usurper's cursed head.