The statement that best explains how a character communicates the author's purpose in The Number Devil is:
The number devil describing numbers as simple reveals that the author's purpose for writing is to persuade.
This statement highlights how the character (the number devil) is presenting mathematics in an approachable light, likely aiming to persuade readers (and Robert) that numbers can be understood and appreciated, which aligns with the author's intent to make mathematics more accessible and enjoyable for readers.