Answer: C. Ariel
Ariel is a spirit that attends to Prospero. Ariel was in the island when Prospero arrived, and he saved the spirit, which is why Ariel is now indebted to him. However, even though Ariel has a kind nature, we do know he would rather be free. This is similar to the situation of people subject to colonialism, as Ariel was the original inhabitant in the island, yet is now a servant of Prospero.