Which term describes groundwater that fills a permeable rock layer?

• A. Underground water
• B. Water vapor
• C. Surface water
• D. Condensation

Answer: (A)

Groundwater is water that fills the spaces in soil and rock beneath the surface. When a permeable rock layer becomes saturated, the water occupying that layer is described as underground water, i.e., groundwater in an aquifer. This is why wells tap into underground water. Water vapor is gas in the air, surface water sits on the surface in lakes and rivers, and condensation is the change from vapor to liquid.