Which characteristic is true of a solution?

A solution is a homogeneous mixture where the components are uniformly distributed at the molecular level. This means that the individual particles of the solute (the substance being dissolved) are mixed thoroughly with the solvent (the substance doing the dissolving) to the point that they cannot be distinguished from each other using the naked eye or even with most optical instruments. This characteristic allows solutions to appear uniform in appearance and composition throughout.

In contrast, other characteristics do not apply to solutions. For example, a mixture that contains solid particles that settle out is typically a suspension, not a solution. Additionally, while some solutions can have a fixed composition, this is not a defining trait of solutions as a whole, since solutions can vary in concentration. Lastly, colloids contain larger particles that can be larger than those found in solutions, leading to a cloudy appearance, which is not a characteristic of a true solution.