Answer:
Option (C)
Step-by-step explanation:
Gray water system refers to the water that is already being used in some other places such as washing machines, dish-washing, bathtubs, and showers. This water does not react with the feces, and it can be recycled and reuse for different purposes such as irrigation and toilet flushing.
As this water can be recycled and reuse, so it helps in consuming less amount of freshwater. It saves a large amount of freshwater that an individual requires every day.
thus, the correct answer is option (C).