Which letter in the diagram corresponds to an area that replenishes an aquifer by precipitation?

Aquifer

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

Precipitation

Any variant of water, solid or liquid, that drops from the atmosphere and makes contact with the Earth, including forms like rain, snow, sleet, and hail.

Diagram

A simplified drawing showing the appearance, structure, or workings of something, often used in educational and technical contexts.