Final answer:
A solution at point C can be saturated, unsaturated, or supersaturated, dependent on whether the concentration of solute is equal to, less than, or greater than the solubility of the solute in the solvent under those conditions. To determine the state, one must compare the solute concentration with its solubility at point C.
Step-by-step explanation:
The solution at point C would best be described depending on its comparison with the solute's solubility at the given conditions. If the concentration of the solute at point C is equal to the solute's solubility in that solvent at that temperature, the solution would be saturated. If the concentration is less than the solubility, it would be unsaturated. If the solution at point C has a higher concentration than the solute's solubility, meaning more solute has been dissolved than would normally be possible under stable conditions, it is considered supersaturated.
If excess solute is added to an unsaturated solution, it will dissolve. If the solution is saturated, it will not. A supersaturated solution is unstable and can result in the excess solute precipitating out suddenly when disturbed. Therefore, without further information on point C, the most precise answer cannot be provided, as it depends on the specific conditions and composition of the solution at this point. However, the concepts of saturated, unsaturated, and supersaturated solutions are defined by how much solute is dissolved compared to the maximum amount the solvent can hold at set conditions.