Measurement of water pollution is made by

The correct option is D

All the above

The correct option is D:

Explanation for the correct option-

1. Presence of coliform bacteria i.e. Escherichia coli indicates the presence of animal excreta in water as these bacteria are primarily found in humans or animal's bodies.
2. Biochemical oxygen demand shows the microorganism number in the water sample on the basis of the presence of organic waste.
3. The pH range of normal water is 6.5- 8.5.
4. Any change in pH indicates the impurity of water.

Final answer: Measurement of water pollution is made by Coliform count, BOD, and pH.