discovering new reservoirs of water in the aquifer reducing water usage through conservation measures combining hydrogen with oxygen to make water piping in water from an aquifer elsewhere
I gave my students this multiple choice question: As the population in an area grows, water usage increases. Eventually, water usage can outstrip the supply. Which measure to increase the amount of available water demonstrates the best stewardship of the resource?

Only one answer is correct among these 4 choices:
- discovering new reservoirs of water in the aquifer
- reducing water usage through conservation measures
- combining hydrogen with oxygen to make water
- piping in water from an aquifer elsewhere

Could you tell me which one is correct?

reducing water usage through conservation measures