Which substance is capable of dissolving the greatest amount of other substances?

Water is often referred to as the "universal solvent" because it has the ability to dissolve a wide range of substances more effectively than most other liquids. This characteristic is primarily due to its unique molecular structure. Water molecules are polar, which means they have a partial positive charge on one side and a partial negative charge on the other. This polarity allows water to interact with and surround various molecules, facilitating their dissolution.

When ionic compounds, such as salts, are added to water, the positive and negative ions are attracted to the opposite charges of the water molecules. This interaction breaks the ionic bonds and allows the ions to disperse throughout the water, effectively dissolving the salt. In contrast, although substances like alcohol can dissolve some solutes and oil can dissolve nonpolar compounds, neither has the same broad capacity for dissolving different types of substances as water does.

Therefore, the recognition of water's properties as a solvent underscores its ability to dissolve a greater variety of substances compared to alcohol, salt, or oil, making it the correct answer in this context.