A rainwater harvesting system can help with?

A rainwater harvesting system is primarily designed to collect and store rainwater, which can be used for various purposes, thereby directly impacting both potable water use and runoff management. By capturing rainwater, the system reduces the reliance on potable water (drinking water) for non-potable uses, such as irrigation or toilet flushing. This is significant because it helps to minimize the consumption of treated water, which is typically more energy-intensive to produce and distribute.

Additionally, by managing stormwater through harvesting, these systems can help to mitigate runoff, which can lead to erosion, water pollution, and flooding. Capturing rainwater prevents it from flowing directly into storm drains and natural waterways, thus helping to manage water quantity and quality issues. This dual benefit of reducing the need for potable water indoors and effectively managing stormwater runoff makes option B the most applicable benefit of a rainwater harvesting system.