Drought is when amount of precipitation decreases, and drought causes famine, which contributes to decentralization and unrest. Given these facts, what can cause famine among the following options:
- Movement of an air mass
 - Effective fertilizers
 - the ground shaking
 - Increased irrigation
 - Crop harvesting
 - Decreased precipitation
 - single-celled organisms
 - forest is destroyed


 

      Decreased precipitation   