Task: Question Generation
Input (English): Background Paragraph: Electric potential energy comes from the position of a charged particle in an electric field. For example, when two negative charges are close together, they have potential energy because they repel each other and have the potential to push apart. If the charges actually move apart, their potential energy decreases. Electric charges always move spontaneously from a position where they have higher potential energy to a position where they have lower potential energy. This is like water falling over a dam from an area of higher to lower potential energy due to gravity. 
Story: David is interested in how electricity works. One day he had two electric charges to investigate, charge A and charge B - both of the charges were negative. He also had two electric fields, field C and field D. He noticed that electric charges were moving from field C to field D.
Output (English): Which field would have lower potential energy, field C or field D?