One end of an unstretched vertical spring is attached to the ceiling and an object attached to the other end is slowly lowered to its equilibrium position. If S is the gain in spring energy and G is the loss in gravitational potential energy in the process, then
A. (a) `S=G`
B. (b) `S=2G`
C. (c) `G=2S`
D. (d) None of the above