Which indicator would best distinguish between a solution with a ph of 3.5 and a solution with a ph of 5.5

Bromocresol green.

Explanation:

Bromocresol green is known as a pH-sensitive triphenylmethane family dye and we can use it for distinguishing between two solutions pH. Below the 3.8 pH containing solution will show yellow color and above 5.4 pH containing solution will show the blue color.

So, a solution which is having pH 3.5, will show the yellow color and in a solution which is having pH 5.5, will show the blue color.