D

Step 1: Understand the definitions of each term provided in the options.
Intermolecular repulsion refers to the forces between molecules that cause them to push each other apart, which relates to the shape at the molecular level but does not directly indicate the material's ability to revert to its original shape after deformation.
Intermolecular behavior is a broad term that describes how molecules interact with each other; it does not specifically address the material's properties related to shape change.
Viscosity is a measure of a fluid's resistance to flow, which is related to its internal friction, but it does not directly discuss changes in shape, volume or length.
Elasticity is defined as the property of a material that allows it to return to its original shape after being deformed by an external force. This aligns perfectly with the question's definition.
Conclusion: Therefore, the correct answer is D: Elasticity.