People usually believe that an argument is nasty and always opposes a concept or initiates disagreement, but in literature, an argumentative piece or essay is merely arguing one's view of a topic and does not have to be rude or disagreeable. Also, arguments can be civilized and kind if they are conducted correctly.
Tone is dependent on the attitude of the author or viewpoint character toward the events of the story
The word best describes the authors attitude toward king's victory over riggs is
b) disbelieving