Viscoelastic behaviour is observed in __________ materials.

ANS:A - non-crystalline organic polymeric

Viscoelastic behavior is primarily observed in non-crystalline organic polymeric materials. Viscoelasticity refers to a material's combined viscous (fluid-like) and elastic (solid-like) behavior, meaning it exhibits both characteristics of fluids and solids when subjected to deformation or stress. Non-crystalline organic polymers, such as plastics and rubbers, often display significant viscoelastic behavior due to their molecular structure. While some ceramics may exhibit viscoelastic behavior under specific conditions, it is less common compared to non-crystalline organic polymers. Crystalline materials generally display more elastic behavior than viscoelastic behavior. Amorphous materials, including non-crystalline organic polymers, are more likely to exhibit viscoelastic behavior compared to crystalline materials. Therefore, the most accurate answer is: non-crystalline organic polymeric materials.