What is ground water primarily composed of?

Groundwater is primarily composed of water that originates from precipitation, such as rain and snow melt, which infiltrates into the soil and percolates through geological formations, ultimately filling the aquifers found underground. This process involves the absorption and movement of water through layers of soil and rock, where it is stored in spaces between particles and within fractures.

This option represents the natural hydrological cycle, illustrating how water moves from the atmosphere to the ground. The water that seeps into the ground becomes part of the groundwater system, providing essential resources for drinking water, agricultural irrigation, and various ecological needs. In contrast to the other options, which describe different sources of water that do not directly contribute to groundwater, the correct answer captures the essence of how groundwater is replenished through natural processes involving precipitation.