5 M is the solution with the highest concentration. Option 1 is correct.
Step-by-step explanation:
The concentration of the solution depends upon the number of moles dissolved in the solution. The number of moles dissolved and volume made upto 1000 ml or 1 litre determines the molarity of the solution.
From the Concentration or molarity of solutions given in the question it can be deduced that solution of 5 M is highest concentrated.
The 5 M solution means that there are 5 moles in 1000ml or 1 litre of the solution.
The solution becomes concentrated when solute quantity is more.