What is the difference between groundwater and surface water?

The distinction outlined in the first choice highlights a fundamental difference between groundwater and surface water. Groundwater refers to water that is found in the saturated zone below the earth's surface, filling the spaces between soil particles and fractures in rocks. This water often accumulates over long periods and can be accessed through wells. On the other hand, surface water is located in bodies of water such as rivers, lakes, ponds, and streams that are above ground. Understanding this difference is crucial as it illustrates how these two forms of water exist in different environments and ecosystems.

While it is true that groundwater can be more susceptible to contamination under certain conditions, this does not constitute a defining characteristic when differentiating the two types of water. Additionally, groundwater is often an important source of drinking water, complementing surface water supplies in many communities, thus refuting the notion that surface water is exclusively used for drinking. Finally, the depth at which groundwater is located can vary significantly, and while it is often deeper than surface water sources, this is not an absolute rule as there can be exceptions based on local geography and hydrology. Therefore, the primary distinction lay in their locations — underground versus above ground, which is captured accurately in the first choice.