If the two rods experience equal extensions, the ratio of

Question

Two steel rods of identical length and material properties are subjected to equal axial rods. The first rod is solid with diameter d and the second is a hollow one with external diameter D and internal diameter 50% of D. If the two rods experience equal extensions, the ratio of  $\frac{d}{D}$                                                                            

         (a) 3/4                         (b) $\frac{\sqrt{3}}{2}$

         (c) 1/2                         (d) 1/4