Infiltration is water entering the soil at the surface; Percolation is downward movement through soil/rock to groundwater.

• A. Infiltration: water entering soil at surface; Percolation: upward movement to atmosphere
• B. Infiltration: downward movement through soil/rock to groundwater; Percolation: water entering soil at surface
• C. Infiltration: water entering soil at surface; Percolation: downward movement through soil/rock to groundwater
• D. Percolation: water evaporates from surface; Infiltration: water stored in groundwater

Answer: (C)

Understanding how water moves from the surface into soil and toward groundwater is being tested. Infiltration is the entry of water from the surface into the soil, while percolation is the downward movement of that water through soil and rock toward groundwater. The correct description matches this sequence: water first infiltrates at the surface, then percolates downward to groundwater. The other options mix up the directions or the processes—for example, upward movement to the atmosphere would be evaporation, not percolation; swapping the definitions would mischaracterize the processes, and claiming percolation evaporates or that infiltration stores groundwater incorrectly pairs the concepts with surface processes. Percolation is a key step in how infiltrated water continues to move downward until it recharges aquifers, so the given pairing accurately reflects the actual flow through the subsurface.