Modulus of section 'z' of hollow circular section with external diameter 'D' and internal diameter 'd' will beAπ/32d(D4 - d4)Bπ/32D(D4 - d4)Cπ/32(D3 – d3)Dπ/32D(D3 - d3)Answer: B. π/32D(D4 - d4)