Final answer:
Character motivation contributes to story urgency by affecting the actions characters take, which drives the plot and engages readers.
Step-by-step explanation:
The best explanation of how a character's motivation contributes to the urgency of a story is that the things characters want affect the actions they will take (Option C). Urgency is driven by the character's motivations which in turn influences how they react to conflicts and challenges in the story. This impetus is critical because it propels the narrative forward and creates a deeper level of engagement for the reader. It is through character's ambitions, desires, and fears that the readers are often drawn into the story, rooting for the outcomes the characters are striving to achieve. Motivation is revealed through dialogue, character relationships, and their actions, which all lead to an understanding of the character's backstory and how they perceive the world around them, thereby contributing to the story's urgency.