Which of the following substances performs the act of dissolving?

The substance that performs the act of dissolving is the solvent. In a solution, the solvent is the component that is present in the greater amount and serves as the medium in which the solute is dissolved. For instance, when sugar (the solute) is mixed with water (the solvent), the water molecules interact with the sugar molecules and break them apart, allowing the sugar to dissolve.

In contrast, the solute is the substance that gets dissolved, while saturated and supersaturated solutions refer to specific states of a solution, indicating how much solute is dissolved at a given temperature. A saturated solution contains the maximum amount of solute that can be dissolved at equilibrium, whereas a supersaturated solution contains more solute than can typically be dissolved under normal circumstances but remains in solution due to certain conditions being met. Therefore, the solvent is the key player in the dissolving process.