A soil sample is underlying a water column of height h₁, as shown in the figure. The vertical effective stresses at point A, B and C are $$\sigma {'_A}$$, $$\sigma {'_B}$$ and $$\sigma {'_C}$$ respectively. Let $$\gamma$$_sat and $$\gamma$$' be the saturated and submerged unit weights of the soil sample, respectively and $$\gamma$$_w be the unit weight of water. Which one of the following expressions correctly represents the sum ($$\sigma {'_A}$$ + $$\sigma {'_B}$$ + $$\sigma {'_C}$$) ?