The correct option is (d) \(\frac{σ_1-σ_3}{2}-\frac{σ_1+σ_3}{2} sinφ=c cosφ\)
The best explanation: The stress condition during plastic equilibrium can be represented by the equation of Mohr-Coulomb,
\(\frac{σ_1-σ_3}{2}-\frac{σ_1+σ_3}{2} sinφ=c cosφ,\)
Where, σ1=major principal stress
σ3=minor principal stress
φ=angle of internal friction.