The Magnitude of the Additional Potential Energy Stored in a Spring

The magnitude of the additional potential energy stored in a spring stretched an additional 2 centimeters from some designated reference length

A) increases as that reference length increases beyond the unstretched length.
B) increases as that reference length increases beyond any length.
C) remains unchanged as that reference length increases beyond the unstretched length.
D) remains unchanged as that reference length increases beyond any length.