9. The overriding idea in any piece of fiction is known as its A. conflict. B. setting. C. theme. D. plot.

The correct answer is C - theme. In any piece of fiction, the theme will be an underlying thought or idea that ties the entire narrative together through connected events or motifs. This theme will be something that is hinted at subtly through other elements of the story such as plot, characters, conflicts, etc and will not be explicitly explained, but the reader will still be very much aware that it is there.