Fact 1: All life relies on a relatively narrow range of pH, or acidity.

Fact 2: All organisms have life cycles.

Given the two facts above, answer the question "what relies on a relatively narrow range of acidity?" with the following options: 
- weathering
 - mammals
 - density
 - Most plants
 - organisms
 - animals
 - barnacles
 - volume


 

     organisms    