Which statement best describes a solution? A). a mixture consisting of minute particles suspended in a medium that start moving about as soon as the mixing process stops. B). a mixture consisting of larger particles suspended in a medium that start settling down as soon as the mixing process stops. C). a mixture having a uniform composition where the components can't be seen separately and all components are in the same state. D). a mixture having a uniform composition but the components can be seen separately and all components are in a different state.

The statement that best describes a solution is the option C: a mixture having a uniform composition where the components cannot be seen separately and all components are in the same state. That is exactly what a solution is: a homogeneous mixture, the composition is uniform, but it can vary from one solution to other. The components must be in the safe phase, but it can be any phase: solid, liquid or gas. The most classical and clear example is the salt solution, NaCl. When you dissolve a spoon of NaCl in water you will not be able to distinguish nor separating the solute from the solvent, and the mixture will have uniform composition.