The given figure shows the relation between void ratio and shear strain for a sand under two density conditions. The void ratio corresponding to the dashed line is called

ANS:B - critical void ratio

The concept Dilation.

Dilation is a process in which void ratio decreases as compaction effort is increased. It occurs in over consolidation clay.
The above falling curve shows the dilation.

In case of normal consolidated clay void ratio increases as compaction effort is increased. Which shown by a rising curve.

Hence the dashed line represents a critical void ratio.