At time t, the hydraulic head corresponding to excess hydrostatic pressure is __________

• A. \(h=\frac{σ’}{γ_w}\)
• B. \(h=\frac{\overline{u}}{γ_w} \)
• C. \(h=\frac{γ_w}{\overline{u}}\)
• D. \(h=\frac{σ’\overline{u}}{γ_w} \)