In "The Crow Child," the author develops a universal theme by illustrating the characters' growth and experiences throughout the story. The most fitting option is:
3. By showing how Cora's mindset toward Ruky has changed by the end.
This choice implies that the story emphasizes character development and the evolution of relationships, which is a common element in stories featuring themes of growing up, responsibility, and familial bonds. Cora's transformation in her views and feelings towards her brother Ruky captures the essence of their shared experiences and the broader themes of love, care, and maturity.