Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R). 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 :
(A)(A) is false but (R) is true
(B)Both (A) and (R) are true and (R) is the correct explanation of (A)
(C)Both (A) and (R) are true and (R) is not the correct explanation of `` ( A ) ``

(D)(A) is true but (R) is false