Based on the excerpt provided, Cora's motivations primarily center around her relationship with her brother, Ruky. The narrative highlights her dual role as both sister and caretaker, indicating that her feelings and actions are deeply connected to his well-being and their shared experiences.
The option that best captures how Cora's motivations advance the plot is:
d. Her desire to be a better sister leads her to take actions that resolve the plot.
This choice highlights Cora's commitment to her brother and suggests that her actions, motivated by her desire to fulfill her role as a sister, will play a significant part in the development and resolution of the story.