You are presented with the question "What can cause famine?" and the following answer choices: 
- Movement of an air mass
 - Effective fertilizers
 - the ground shaking
 - Increased irrigation
 - Crop harvesting
 - Decreased precipitation
 - single-celled organisms
 - forest is destroyed

Now knowing that drought is when amount of precipitation decreases and drought causes famine, which contributes to decentralization and unrest, choose the best answer.


 

      Decreased precipitation   