What defines a saturated solution?

A saturated solution is defined as one that has reached its maximum solute concentration at a specific temperature and pressure. This means that at that given set of conditions, no additional solute can be dissolved in the solvent; any extra solute added will remain undissolved. This characteristic stems from the dynamic equilibrium established between the solute particles that are dissolved and those that are insoluble.

In contrast, the other options do not accurately describe a saturated solution. A solution with no solute would simply be the pure solvent. A highly concentrated solution would imply that it contains a large amount of solute, but it may or may not be at the saturation point. Lastly, a solution that can still dissolve more solute indicates that it is unsaturated, meaning more solute can still be added to reach saturation. Thus, the key element defining a saturated solution is the maximum concentration of solute that can be maintained in equilibrium with its undissolved form.