Which of the following questions should you ask in order to understand an author's tone?

"Are these positive or negative words?" is the question that should be asked in order to understan an author's tone. Option C is correct.

Tone in writings, stories, or plays refers to the attitude of a writer toward a subject or an audience. Tone is typically conveyed through the choice of words, or the viewpoint of a writer on a particular subject.

In fiction, tone is the narrator’s attitude toward the text while in non-fiction, it is the writer/speaker’s attitude toward his subject.

ah, shun the horrid gulf! by scylla fly.