Explanation: The elasticity of a material is determined by its ability to return to its original shape after being deformed. Steel, being a metal, has a high modulus of elasticity and requires a larger deforming force to change its shape, but it also has the ability to return to its original shape once the force is removed. Rubber, on the other hand, is a polymer with a lower modulus of elasticity, meaning it is easily deformed and doesn't return to its original shape as effectively as steel.