For both plane stress as well as plain strain case the equilibrium equation in z-direction is _______

• A. \(\frac{∂τ_{xz}}{∂x}+\frac{∂σ_z}{∂z}+γ=0\)
• B. \(\frac{∂σ_x}{∂x}+\frac{∂τ_{zx}}{∂z}+γ=1\)
• C. \(\frac{∂σ_x}{∂x}+\frac{∂τ_{yx}}{∂y}+γ=0\)
• D. \(\frac{∂σ_x}{∂x}+\frac{∂τ_{zx}}{∂z}=0\)