Which characteristic of orthodontic wire describe energy storage capacity?
Range
Resilience
Formability
Proportional limit
Popularly, the term resilience is associated with springiness, but it means precisely the amount of energy absorbed within a unit volume of a structure when it is stressed to its proportional limit. 
The resilience of two or more materials can be compared by observing the areas under the elastic region of their stress-strain plots assuming that they are plotted on the same scale. The material with the larger elastic area has higher resilience.
Key Concept:
Resilience—The amount of elastic energy per unit volume that is sustained on loading and released upon unloading of a test specimen.
 
Reference: Phillips science of dental materials, 12th ed page no 48,55