Assertion $(A)$:The stretching of a spring is determined by the shear modulus of the material of the spring.
Reason $(R)$:A coil spring of copper has more tensile strength than a steel spring of same dimensions.
In the light of the above statements, choose the most appropriate answer from the options given below:


(Take, $g =9.8\,ms ^{-2}$ and $\left.\pi=\frac{22}{7}\right)$