What is groundwater?

Groundwater is defined as water that has seeped down below the earth's surface, filling the cracks and spaces in soil, sand, and rock. It is stored in underground formations known as aquifers, which can hold significant quantities of water that are slowly replenished through processes such as precipitation and infiltration. Groundwater plays a crucial role in the water cycle, providing a reliable source of water for various uses, including drinking, agriculture, and industry.

The other options pertain to water in different contexts: water found in oceans and rivers is surface water, while water used in agriculture and irrigation encompasses multiple sources, including both surface water and groundwater. Evaporated water refers to the process of water turning into vapor and rising into the atmosphere, which is unrelated to the concept of groundwater. Thus, identifying groundwater specifically as the water that has penetrated below the earth's surface is key to understanding its importance and function within the broader hydrological system.