An author's argument is the opinion or belief that he or she wants to persuade readers to believe.
The right answer is C (Hail, king, for so thou art: behold, where stands/The usurper's cursed head:)
Uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu