maximum shear stress

Question

The state of plane-stress at a point is given by$\sigma_x$ = 200 MPa, $\sigma_y$ = 100 MPa and $\tau _{xy}$=100 MPa.The maximum shear stress (in MPa) is

(a) 111.8           (b) 150.1              (c) 180.3             (d) 223.6