Which statement best defines porosity, permeability, and their combined role in groundwater movement?

• A. Porosity measures rock hardness; permeability measures color.
• B. Porosity and permeability describe only solids; not related to groundwater.
• C. Porosity is the fraction of void space in a rock; permeability is the ease with which fluids move through the rock; together they determine how much water a rock can store and how quickly groundwater can move.
• D. Porosity equals permeability.

Answer: (C)