The Question and Answer section for The Tempest is a great resource to ask questions, find answers, and discuss the novel.
Ariel takes away his banquet and makes his sword really heavy.
Caliban wants Stephano to murder Prospero. In return, he promises to serve Stephano. Caliban will still be enslaved under Stephano. It is also highly unlikely that a bumbling Stephono can kill a near omnipotent wizard.
I might consider:
B. He uses the island and the storm as reasons for Prospero to tell Miranda his backstory, which introduces the audience to the story’s central conflict.