ANS:C - Steel

Among the options provided, steel is the most elastic material. Elasticity is the property of a material to deform under stress and return to its original shape when the stress is removed. The degree of elasticity depends on the material's Young's modulus, which is a measure of its stiffness. Steel has a high Young's modulus compared to the other materials listed (plastic, glass, and rubber), indicating that it can undergo deformation under stress while still returning to its original shape when the stress is removed. This makes steel the most elastic material among the options provided. Plastic, glass, and rubber typically have lower Young's moduli compared to steel and exhibit greater deformation under stress, with less ability to return to their original shape after deformation.