From macbeth:

which of these lines provides important information for the exposition of the play?

1. o banquo, banquo! /our royal master's murder'd!

2. and, for an earnest of a greater honor,/he bade me, from him, call thee thane of cawdor

3. thou know'st that banquo, and his fleance, lives.

4. hail, king, for so thou art: behold, where stands/the usurper's cursed head: