For the plane stress situation shown in the figure, the maximum shear stress and the plane on which it acts are:
- $-50$ MPa, on a plane $45^{\circ}$ clockwise w.r.t. $x$-axis
- $-50$ MPa, on a plane $45^{\circ}$ anti-clockwise w.r.t. $x$-axis
- $50$ MPa at all orientations
- Zero, at all orientations