The correct option is A saturation
Saturation point is the stage at which a solvent cannot dissolve any more of the solute and the additional amounts of it will appear as a separate phase.
The solution at this stage is called as a saturated solution.
If more solute is dissolved to the saturated solution at higher temperatures, then the solution is called as supersaturated solution.
If a solution has not yet attained the saturation point, it is called as an unsaturated solution.