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

Fact 2: Life during most of the Precambrian was restricted to bacteria and algae.

Given the two facts above, answer the question "Bacteria relies on a relatively narrow range of what?" with the following options: 
- RNA
 - Fe
 - 12
 - DDT
 - DNA
 - pH
 - CO2
 - O2


 

      pH   