Final answer:
The image of Amaroq licking a wolf cub (D) best represents the theme 'Every creature has a crucial role to play' by conveying the importance of every organism within an ecosystem.
Step-by-step explanation:
In the context of the book Julie of the Wolves and the theme "Every creature in the world has a crucial role to play," the image that would best represent this theme is D. Amaroq licking a wolf cub. This act illustrates the important role every member of an ecosystem plays—Amaroq, as a wolf, and his cubs contribute to their environment. Wolves are apex predators and play a key role in controlling the populations of other animals, which helps maintain a balanced ecosystem. This reflects the significance of each creature's role in the web of life, similar to the iconic story of the Capitoline She-wolf feeding the twins Romulus and Remus, which is a symbol of nurture and growth in Roman mythology.