After which action would the concentration of a solution remain constant?(1 point)

The concentration of a solution would remain constant after "adding water to the solution."

When you add water to a solution, you dilute it, but the concentration can remain constant if the proportions of solute and solvent are adjusted appropriately. In this case, you would be adding an equal amount of solute to maintain the same ratio if that was intended. Otherwise, concentration generally changes with the other actions listed.