What is a substance that can dissolve other substances?

The correct answer is a substance that can dissolve other substances, which is referred to as a solvent. A solvent is typically a liquid that facilitates the dissolution process, allowing solutes to be evenly distributed within the solution. This characteristic of solvents is critical in various chemical processes and everyday applications, such as in the preparation of solutions for laboratory experiments or in cooking.

The role of a solvent is to interact with the solute at a molecular level, pulling apart and surrounding solute particles to effectively dissolve them. For example, water is often called the "universal solvent" because it can dissolve a wide variety of ionic and polar substances.

In contrast, the other choices represent different concepts. A disperser refers to a substance that helps to distribute solid particles throughout a liquid, but it does not inherently dissolve them. A solute is the substance that is being dissolved in a solvent. A reagent is a substance used in a chemical reaction but does not specifically imply the ability to dissolve other substances. Thus, understanding the role of a solvent provides essential insight into many scientific and practical scenarios involving solutions.