Concept:The spirits are the strange shapes that bring the banquet in this scene, and they vanish when the show is interrupted.
Explanation:In the extract, the speaker reflects on the existence of such marvellous creatures, which are now seen before the nobles.
These spirits act under Prospero’s command and present the banquet.
However, the magical banquet is not permanent.
When Ariel appears in the form of a harpy, the banquet disappears with thunder and lightning.
The spirits themselves also vanish from the stage at that moment.
They are not killed, nor do they remain on stage.
They also do not continue to serve in that scene after the vanishing.
Therefore, the most accurate description of what happens to the spirits is that they disappear.
Answer:D. they disappear