(a) 6.5 – 7.5

(b) 2.0 – 3.5

(c) 3.5 – 5.0

(d) 9.0 – 10.5

Correct option – ( a )

Explanation – for the life of the freshwater plants and animals the pH of water should neither be acidic nor basic , that is it should be basic . So the range will be 6.5 – 7.5