Answer: D. Replacing thermal power plants.
Step-by-step explanation:
Thermal Power Stations are some of the biggest users of water in the world because water is integral to producing electricity in them. These stations burn fossil fuels like coal which then vaporizes water so that it becomes steam which then drives turbines that produce electricity.
Water is also used for cooling high temperatures produced.
If these thermal stations are replaced with something that uses less water, it will go a long way in keeping the water debt less than the water supply.