Elastic deformation is a material deformation by a force that returns to its original dimensions after the force is removed.

• A. A permanent change in shape after loading.
• B. The rate at which a material deforms under load.
• C. A material deformed by a force returns to its original dimensions after the force is removed.
• D. The failure of a material under cyclic loading.

Answer: (C)

Elastic deformation is the reversible change where a material changes shape under an applied force but goes back to its original dimensions once the load is removed. This occurs when the stress is within the elastic limit, and the relationship between stress and strain is linear (Hooke’s law), with stiffness described by Young’s modulus. The statement matches this idea, so it’s the correct description. The other ideas describe different phenomena: a permanent change after unloading is plastic deformation; deformation rate describes how fast the material deforms (strain rate or viscoelastic effects); and fatigue is failure under repeated or cyclic loading rather than reversible deformation.