Expressing concentrations in terms of molarity is especially convenient since it allows one to count chemical particles by measuring

C) the volumes of solutions.

Explanation:

Molarity is a unit of concentration and the molarity of a solution is expressed as the number of moles of solutes that is present in one liter of solution.

Mathematically, molarity is expressed as: mole of solute/volume of solution (L).

This unit of concentration is convenient because it allows one to count chemical particles in a certain amount of solution by measuring the volume of that solution.

For example, if a solution has a concentration of 1 M, it means that 1 mole of solute is present in 1 liter of the solution. If 0.5 liter of the solution is taken, it means it contains 0.5 mole of solutes, 0.25 liter of the solution will contain 0.25 mole solute, etc.