ANS:B - which gets polarised, when stressed.

The statement "piezoelectric is a material which gets polarized when stressed" refers to the piezoelectric effect, a phenomenon exhibited by certain materials in response to mechanical stress. When a mechanical force is applied to a piezoelectric material, such as compression, tension, or shear stress, it causes the material's internal structure to deform asymmetrically, resulting in the separation of positive and negative charges within the material. This separation of charges creates an electric polarization within the material, with one side becoming positively charged and the other negatively charged. The piezoelectric effect is a reversible process, meaning that when the mechanical stress is removed, the material returns to its original shape and the electric polarization disappears. Conversely, when an electric field is applied to a piezoelectric material, it undergoes a mechanical deformation, changing its dimensions. This bidirectional coupling between mechanical and electrical properties makes piezoelectric materials valuable for various applications, including sensors, actuators, transducers, and energy harvesting devices. In summary, the piezoelectric effect describes the ability of certain materials to generate an electric polarization in response to mechanical stress, and this phenomenon is exploited in numerous technological applications.