The rest of Earth's precipitation that isn't evaporated or doesn't soak into the soil is ______.

• A. Runoff
• B. Groundwater
• C. Ponds and lakes
• D. Precipitation

Answer: (A)

After a rainfall, water on land can follow several paths. Some of it evaporates back into the atmosphere, some infiltrates the soil to replenish groundwater, and the remaining water that can't soak in or evaporate flows over the surface toward streams, rivers, and lakes. This overland flow is called runoff. It explains why runoff is the residue of precipitation that doesn’t return to the air as evaporation and doesn’t soak into the ground. Groundwater is the water that has infiltrated and moved underground, while ponds and lakes are bodies that can collect runoff. Precipitation is the input that starts the whole cycle, not the remaining portion after other processes.