In a beam of uniform strength the extreme fiber at every cross section are stressed to the maximum allowable stress. Consider a solid circular beam of uniform strength subjected to bending moment. In this beam, the diameter of the cross-section at any sectional is proportional to (A) a cube root of the bending moment at that section (B) the square root of the bending moment at that section (C) the bending moment at that section (D) inversely to the bending moment at that section