ANS:B - 200

The term "rubber" refers to a specific subset of elastomers that exhibit exceptional elasticity and flexibility. Elastomers, in general, are polymers that can undergo significant deformation and then return to their original shape when the deforming force is removed. They are characterized by their ability to stretch to a considerable extent without permanent deformation. The threshold of 200% for percentage elongation is often used to distinguish rubber from other elastomers. This means that when subjected to a tensile force, rubber materials can elongate to at least double their original length before breaking. This level of elongation is a significant criterion for defining rubber because it indicates the material's exceptional stretchability and flexibility, which are key properties of rubber that make it suitable for various applications such as tires, seals, gaskets, and many more.