In a machine component the state of stress at a critical region is given below. The yield strength is 300 MPa, ultimate strength is 400 MPa and Poisons ratio is 0.28 for the material. Compare the factor of safety based on the following failure theories. 100 50 0 [o] 50 100 0 0 0 0 (P) Principal stress theory (Q) Shear stress theory (R) Von mises stress theory (a) P = Q = R (b) P = Q < R (c) P < Q < R (d) P < Q = R