When an open coiled helical compression spring is subjected to an axial load (W), the compression produced in the spring will be (where, n = No. of active turns of the spring and G = Modulus of rigidity for the spring material)

A. $$\frac{{2{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{G}}{{\text{d}}^4}}}$$

B. $$\frac{{4{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{G}}{{\text{d}}^4}}}$$

C. $$\frac{{8{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{G}}{{\text{d}}^4}}}$$

D. $$\frac{{16{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{G}}{{\text{d}}^4}}}$$

Answer: Option C