How did the southwestern United States become suitable for agriculture?

• A. Irrigation
• B. Deforestation
• C. Climate shift
• D. Monsoon cycles

Answer: (A)

The key idea is that water management makes farming possible where rainfall is scarce. In the desert Southwest, rainfall is light and irregular, so crops would fail without a reliable water source. Irrigation solves this by moving water from rivers, lakes, or reservoirs to fields, creating a steady supply for crops. Ancient peoples built canals and later developed large-scale water projects to distribute water across valleys and plains, turning arid landscapes into productive farmland. This ability to control and deliver water is what enabled agriculture to take root in the region.

Deforesting doesn't create water for crops and can actually harm soil and moisture retention. Climate shifts or monsoon cycles aren’t dependable mechanisms in the Southwest; even when rains occur, they aren’t enough on their own to sustain agriculture without irrigation.