The ability of a material to resist deformation or deflection under stress is known as-

Correct option is D

Stiffness is the ability of a material to resist deformation or deflection under stress. It is a measure of how much a material deforms under a given load. Materials with high stiffness deform less when subjected to a force, making them ideal for applications where minimal deflection is required. Stiffness is an important property in structural engineering and materials science.