Answer:
It's aquifier.
Explanation:
Precipitation is at the top because it any form of water that falls from clouds and reaches Earth's surface. It is not aquitard because that is a slab of impervious surface at the bottom of an aquifer that does not allow water to go through and is at the bottom of the image. The arrow is the gravity, so the only thing left is aquifier, a permeable layer of rock and sediment that stores and brings groundwater in enough quantities to supply wells.
