You are presented with the question "Bacteria relies on a relatively narrow range of what?" and the following answer choices: 
- RNA
 - Fe
 - 12
 - DDT
 - DNA
 - pH
 - CO2
 - O2

Now knowing that all life relies on a relatively narrow range of pH, or acidity and life during most of the Precambrian was restricted to bacteria and algae, choose the best answer.


 

      pH   