What Was the Painting Called the Nightmare Based On

What was the painting called The Nightmare based on?

A) bad dreams the artist frequently had about creatures and damsels in distress
B) the legend of a male demon that has sex with people while they sleep
C) a fairy tale the artist heard every night before bed when he was a child
D) a fireworks display the artist saw when he was in London
E) none of the other answers