How is "rebuttal" used in argumentation?

Read the passage. macduff. hail, king! for so thou art: behold, where stands th’ usurper’s cursèd head. the time is free. i see thee compassed with thy kingdom’s pearl, that speak my salutation in their minds, whose voices i desire aloud with mine: hail, king of scotland! what is the main idea of this passage from act v of the tragedy of macbeth by william shakespeare? macduff is hailing macbeth as the rightful king of scotland. macduff anticipates that he will be king. macduff anticipates that king duncan will be king. macduff is acknowledging that macbeth is a traitor to the throne.