One end of a light spring of spring constant k is fixed to a wall and the other end is tied to a block placed on a smooth horizontal surface. In a displacement, the work done by the spring is `+(1/2)kx^(2)`. The possible cases are.
A. the spring was intially compressed by a distance `x` and was finally in its natural length.
B. it was initially strecthed by a distance `x`, and finally was in its natural length.
C. it was initially in its natural length and finally in a compressed position.
D. the spring was initially compressed by a distance `x` and finally stretched by `x`
