For a triangular and uniformly distributed semi-infinite loads, the vertical stress σz is given by ___________

• A. \(σ_z=\frac{q}{aπ}[xα+z] \)
• B. \(σ_z=\frac{q}{aπ}(aβ+xα) \)
• C. \(σ_z=\frac{q}{π} \left[\frac{az}{a^2+z^2}\right]\)
• D. \(σ_z=[xα-\frac{az}{(x-α)^2+z^2}(x-α)]\)