Final answer:
Carrie Kelley's naivety and trustworthiness make her a suitable Robin.
Step-by-step explanation:
Carrie Kelley's naivety and trustworthiness are defining characteristics that make her a suitable Robin. While it may seem like a disadvantage at first, her innocence allows her to hold onto her optimism and pure intentions, which are crucial for a young superhero. In Frank Miller's 'The Dark Knight Returns' comic series, Carrie's unwavering belief in Batman's cause and her determination to make a positive difference in Gotham City ultimately reinforce her value as Robin.