A clay soil sample is tested in tri-axial apparatus in consolidated drained conditions at a cell pressure of $$\frac{100 KN}{m^{2}}$$ What will be the pore water pressure at a deviator stress of $$\frac{40 KN}{m^{2}}$$

A

$$\frac{0 KN}{m^{2}}$$

B

$$\frac{20 KN}{m^{2}}$$

C

$$\frac{40 KN}{m^{2}}$$

D

$$\frac{60 KN}{m^{2}}$$