What does "concentration" refer to in a solution?

Concentration in a solution specifically refers to the amount of solute present in a given volume of solution. This means it quantifies how much of the dissolved substance (solute) is contained within a specific amount of the overall mixture (solution). It is commonly expressed in various units such as moles per liter (molarity) or grams per liter, which illustrates the proportion of solute to the solvent.

Understanding concentration is crucial for various applications in chemistry, including reaction rates, solubility, and determining the appropriate amounts needed in chemical reactions and analyses. The other options do not accurately describe concentration; for example, the volume of the solvent used or the stability of the solution concerning temperature are not measures of concentration, nor does total mass reflect the specific amounts of solute versus solvent. Therefore, option B is the most accurate representation of what concentration means in the context of solutions.