The correct answer is letter D; you will find the explanation underneath.
The plot suggested by Caliban to kill Prospero starts when he tells his friends to take Prospero's magic books.
Once this first action takes place, they can kill Prospero and take his daughter. Therefore, Stephano will be the king of the island, and Miranda will become the queen.
Trinculo expresses his agreement to Stephano, by saying that he thinks the plan is a good idea; at the same time Stephano apologizes for the previous bickering.
Caliban also tells them that Prospero will be asleep in about thirty minutes.
