13. Which is the most significant sentence in the
introductory paragraph? ψ(｀∇´)ψ

The Thesis statement or claim

Explanation:

First sentence answers the question or provides a thesis for an argument

An author may choose to create flat characters (those without  any depth to them), round characters (those who are completed), dynamic characters (those who change throughout the novel), and static characters (those who do not). I guess that characters can also be energetic, but definitely not cube and triangle.