* Solutions are homogeneous mixtures where one substance (the solute) dissolves completely into another substance (the solvent). In the case of water samples with dissolved substances, the water acts as the solvent and the dissolved substances are the solutes.

Let's look at the other options:

* Heterogeneous mixtures have visible, distinct components that don't blend uniformly. This isn't the case with dissolved substances in water.

* Chemical mixtures are a broader category that includes solutions, suspensions, and colloids.

* Suspensions have particles that are large enough to settle out over time. While some water samples might contain suspended particles, dissolved substances remain evenly distributed.

Therefore, "solutions" is the most accurate term to describe water samples with dissolved substances.