What does dilution refer to in terms of solution concentration?

Dilution is defined as the process of reducing the concentration of a solute in a solution, typically by adding more solvent. When a solution is diluted, the amount of solute remains the same, but its concentration decreases because the total volume of the solution increases. This results in a less concentrated solution compared to the original.

In the context of the options provided, acknowledging that the dilution process results in a solution or series of solutions with a reduced concentration of solute aligns perfectly with the definition of dilution. Thus, the correct answer effectively captures this crucial chemical principle, making it an essential concept in areas such as chemistry and biological sciences where accurate solution concentrations are vital.