Correct option is B
The phreatic line (also known as the seepage line) is the boundary within an earthen dam or embankment where the pressure changes from positive to atmospheric. Below this line, the pore water pressure is positive (greater than atmospheric pressure), and above it, the pressure is negative or zero.
This line is critical in analyzing the stability of a dam, as it demarcates the saturation zone within the dam.
The area below the phreatic line is fully saturated and exhibits positive hydrostatic pressure, whereas the area above it is unsaturated.
