ANS:A - applies to elastic deformation.

"Applies to elastic deformation" means that Hooke's law describes the behavior of materials when they are subjected to small deformations that are fully reversible, meaning that when the applied stress is removed, the material returns to its original shape and size. In elastic deformation, the material responds to an applied stress by deforming, but it does so in a linear and reversible manner. This means that as the stress increases, the material deforms proportionally, and when the stress is removed, the material returns to its original undeformed state. Hooke's law specifically states that within the elastic limit of a material, the stress (force per unit area) applied to it is directly proportional to the strain (change in length per unit length) it undergoes. Mathematically, this relationship can be expressed as: Stress=E×Strain Where:

• StressStress is the applied stress.
• StrainStrain is the resulting strain.
• E is the modulus of elasticity, also known as Young's modulus, which represents the stiffness of the material.

In summary, Hooke's law applies to elastic deformation by describing the linear relationship between stress and strain within a material's elastic limit. This law provides a fundamental understanding of how materials behave under small deformations and is widely used in engineering and materials science to analyze and design structures and components.