Answer: A. He uses Caliban to do menial physical labor, while he uses Ariel to carry out his magical schemes.
In The Tempest, Ariel and Caliban seem to be in a similar situation. They are both inhabiters of the island, and both are servants to Prospero. However, it is clear that their relationship with their master is a very different one. Ariel is certainly more appreciated by Prospero, and he mostly helps with Prospero's magical schemes. Ariel is, for the most part, grateful and loyal to Prospero. On the other hand, Caliban is forced to do menial job, and he despises Prospero. His only wish is to be free of him.