The largest concentration doesn't depend on there being the most water salt but the most salt per unit of water
I would write ratios for each to see how much water there is per teaspoon of salt
Solution 1: 1tsp to 25mL
Solution 2: 1tsp to 25mL
Solution 3: 1tsp to 30mL
So in this case solutions 1 and 2 have the same larger concentration and solution 3 has a smaller concentration
Hope this helps