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: 
- organisms
 - carbon
 - animals
 - hydrogen
 - density
 - trees
 - Most plants
 - barnacles


 

 organisms        