A shaft can carry a torque of 5 kN-m and a bending load of 5 kN.m with a factor of safety based on maximum shear stress theory as 2. If the shaft is subjected to a torque of 8.5 kN-m and a bending load of 1.5 kN-m, the corresponding factor of safety is (a) 2 (b) 1.8 (c) 1.6 (d) 1.4