A Spring in Equilibrium Is 4 Meters Long and an External

Multiple Choice

A spring in equilibrium is 4 meters long and an external force of 8 Newtons stretches the spring to a length of 4.5 meters. The work done by the spring in stretching it from 4.5 meters to 5 meters, in Newton-meters, is
​

A) -22
B) -17
C) -13
D) -9
E) -6