Fact 1: Changes in the pH of soil can cause plants to die.

Fact 2: Famines are extreme shortages of food that cause people to die of starvation.

Given the two facts above, answer the question "Changes in what can cause extreme shortages of food?" with the following options: 
- pH of soil
 - Dehydration
 - climate
 - colder weather
 - global warming
 - salinity
 - Time and energy
 - Winter


 

 pH of soil        