What is the term for porous,water-saturated layers of underground rock? 

A)  an aquifer 
B)  a runoff area 
C)  a recharge area 
D)  a watershed

Aquifer

An underground layer of water-bearing permeable rock, rock fractures, or unconsolidated materials from which groundwater can be extracted using a water well.

Porous Layers

Geological formations consisting of rocks, soil, or sediment that have a high porosity, allowing for the passage and storage of fluids such as water and oil.

Underground Rock

Underground rock refers to rock formations that exist beneath the Earth's surface, playing a critical role in various geological processes and resource reservoirs.