What characterizes the stress-strain behavior of a material in the region where plastic deformation begins?
When plastic deformation begins, the material experiences permanent deformation, meaning it does not return to its original shape even after the load is removed. As per NCERT, applying relevant law/formula with correct units and sign convention leads to The material experiences permanent deformation. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: NCERT Class 11 Physics, Thermal Properties and Gravitation.