A bar of rectangular cross-section (b × 2b) and another bar of circular cross-section of diameter d with the same length, are made of same material, and are subjected to same bending moment and have the same maximum bending stress developed. The ratio of weights of the rectangular bar and circular bar will be

• A. \(\frac{(2\pi)^3}{3\pi}\)
• B. \(\sqrt{\pi}\)
• C. \(\sqrt{3\pi}\)
• D. \(\frac{(3)^\frac{2}{3}}{2(\pi)^\frac{1}{3}}\)