In a Problem Using Energy Considerations to Solve for the Speed

Multiple Choice

In a problem using energy considerations to solve for the speed of a ball thrown from the top of a building when it strikes the ground below,where should the potential energy have its zero value?

A) It should be at the level from where the ball is thrown.
B) It should be at the ground level where the ball hits.
C) It should be slightly below ground level so the potential energy is always positive.
D) It doesn't matter since only differences in potential energy matter in solutions.