The right answer is D

A bio retention pond helps with rainwater management by slowing the rate at which rainwater leaves the location.

A septic system doesn’t reduce potable water use. It reduces the amount of wastewater that has got to be treated by municipal sewage plants.

Increasing the infiltration of runoff doesn’t reduce potable water use. It only improves the standard of the runoff.

A dual flush toilet has two different flow rates depending on the type of waste. These toilets can use less potable water than a typical toilet.