Groundwater is defined as:

The definition of groundwater pertains specifically to water that exists beneath the Earth's surface. This water is typically found in the soil and in geological formations known as aquifers, where it is stored in pore spaces between soil particles and sediment. Groundwater plays a crucial role in the hydrologic cycle, supplying water to wells and springs, and is a vital resource for agricultural and drinking water.

Understanding the alternative choices helps clarify why they do not define groundwater. Water stored in glaciers refers to freshwater kept in ice formations, and this is not classified as groundwater. Water found on the Earth's surface, such as in rivers, lakes, or wetlands, is surface water, which is distinct from groundwater. Saltwater in oceans is a separate category, characterized by its saline content, and does not pertain to groundwater, which is generally freshwater. Thus, option C accurately captures the essence of groundwater as it is located beneath the surface in the soil and geological formations.