Fact 1: Most people can survive only a few days without water.

Fact 2: Water is everywhere H20.

Given the two facts above, answer the question "What do most people need at least a little of every few days to survive?" with the following options: 
- NACL
 - UV
 - mL
 - oxygen
 - corn
 - H20
 - rest
 - Hydrogen


 

      H20   