This one is kinda hard. I would say B or C. Use the one you would use in a paragraph about it.
Answer:
Why is the Sky Tree important to the people in Sky Land? It provides them with shade. It provides food for them.
Whats the question asking
The correct answer should be the morality play. They would usually feature various personified emotions, beliefs, values, and a protagonist would meet them and achieve something greater with their help.