The correct answer is D. All follow.
The statement says that the drinking water supply to New Bombay has been suspended due to pollution of the Patalganga river. The courses of action are:
I. The industries responsible for discharging effluents into the river should be asked to close down immediately.
II. The river water should immediately be treated chemically before resuming supply.
III. The Pollution Control Board should check the nature of effluents being discharged into the river by industries at regular intervals.
All of these courses of action are necessary to ensure that the drinking water supply to New Bombay is safe and reliable.
Course of action I is necessary to stop the pollution of the river. If the industries are not closed down, they will continue to discharge effluents into the river, which will make the water unsafe for drinking.
Course of action II is necessary to treat the river water before it is supplied to the people of New Bombay. This will ensure that the water is safe to drink.
Course of action III is necessary to prevent the pollution of the river in the future. The Pollution Control Board should regularly check the nature of the effluents being discharged into the river by industries and take action against any industries that are found to be polluting the river.
Therefore, all of the courses of action are necessary to ensure that the drinking water supply to New Bombay is safe and reliable.