I think you need to pick a different book....
C) partially . Because it’s important but not as important. If it was an overall things that were unhealthy then that’s a different story.
The definition of "tone" in literature is the way the author expresses his attitude through his writing. The tone can change very quickly or may remain the same throughout the story. Tone is expressed by your use of syntax, your point of view, your diction, and the level of formality in your writing.