What is an aquifer?

An aquifer is defined as a geological formation capable of holding and transmitting water. This characteristic is crucial because aquifers serve as important sources of groundwater, which is essential for drinking water supplies, irrigation, and various industrial processes. Typically composed of permeable materials such as sand, gravel, or certain types of rock, aquifers allow water to flow through them, making it accessible for extraction. Understanding the properties of aquifers, including their capacity to recharge and sustain water supply, is vital for effective water resource management and ensuring a sustainable supply of potable water.

The other options describe different water-related concepts but do not accurately define an aquifer. For instance, the first choice mentions a layer of rock that cannot hold water, which describes impermeable layers rather than aquifers. The second option refers to surface water collection sources, which are distinct from groundwater aquifers. The last option addresses bodies of saltwater, like oceans, which do not relate to the concept of aquifers and their capacity to store freshwater.