To determine which solution exhibits the greatest concentration of salt, we would need specific information about the concentrations of each solution (typically given in terms of molarity, mass/volume percentage, or another measure). Since that information is not provided in your question, I cannot give you an accurate answer.
If you could provide the concentrations or any other relevant data for Solutions A, B, C, and D, I'd be happy to help you figure out which has the greatest concentration of salt!