A circular rod of 20 mm diameter carries a pull along a line which is parallel to its centroidal axis, but is displaced from it. Determine the distance of the line of pull form the centroidal axis, if the maximum stress is 20 percent greater than the mean stress on a section normal to the axis. (a) 0.2 mm (c) 0.7 mm (b) 0.5 mm (d) 0.9 mm