Answer:
The correct option is letter D.
Step-by-step explanation:
Authors use character traits to A) develop round characters because this way, the character is congruent most of the times and well-defined by aspects given by the author; b) to provide insight characters so the reader can understand what they think about specific situation or why they took specific decisions, which leads to C) to help explain why they act a certain way, so their behavior is always logical according to the text and the situation.