Two students evaluate the gravitational potential energy of a 0.50kg ball resting on a table 1.0m above the floor. Student A chooses the floor as the zero of potential energy, while Student B chooses the ceiling, which is 3.0m above the floor. Let UA and UB be the values each student assigns to the ball at rest on the table. Which statement best describes the relationship between UA and UB?
a) UB equals UA because potential energy cannot depend on the arbitrary choice of zero level.
b) UB is 14.7J greater than UA, so Student B will always predict larger changes in potential energy.
c) UB is 14.7J less than UA, but both students will calculate identical changes in potential energy.
d) UB is negative, making Student B’s reference choice physically meaningless.