Which inference is best supported by these lines? . . . I must Once in a month recount what thou hast been, Which thou forget'st. This dam'd witch Sycorax, For mischiefs manifold and sorceries terrible To enter human hearing, from Argier, Thou know'st, was banish'd: for one thing she did They would not take her life. Is not this true?

Prospero had previously defeated the witch Sycorax.
Prospero uses psychological manipulation to control Ariel.
Ariel is accompanied throughout the play by music and song.
Ariel wants Prospero's approval and does his best to please him.