The core diameter of the screw is 40 mm. The shear stress due to this torque in the power screw is

Question

In a power screw square threads the torque required  to rise the given load is found to be 8800 N – m. The core diameter of the screw  is 40 mm. The shear stress due to this torque in the power screw is

(a) 350 N/mm²                (b) 700 N/mm²

(c) 175 N/mm²                (d) 525 N/mm²