Precipitation moves down into the soil and becomes groundwater .groundwater that travels into the saturated soil zone becomes part of the

-can be measured directly
-inject dye in one well and observe where dye appears in other wells
-determines velocity and direction of groundwater flow
-carbon - 14 can date groundwater at various wells
-determines how long since water entered groundwater system

Cbecause it is the only one describing a habitat

The type of rock she find is a sediment rock