The correct answer is C) He plays a musical tune yet remains invisible.
What Ariel did that caused fear in the hearts of Stephano and Trinculo was "He plays a musical tune yet remains invisible."
We are talking about "The Tempest," a play written by renown English writer William Shakespeare.
In the story, Prospero conjures and creates a magical storm to shipwreck a vessel that transported his brother Antonio and the King of Naples. Propero has a loyal servant called Ariel. Ferdinand, the son of the king, falls in love with Miranda, the daughter of Prospero. And then the conflict of the plot develops.