Fact 1: Animals require water for survival.

Fact 2: Hydrogen and oxygen create water.

Given the two facts above, answer the question "which are required for animal survival?" with the following options: 
- hydrogen and oxygen
 - Chemical energy
 - oxygen and methane
 - critical organs
 - sense organs
 - hydrogen and helium
 - light and dark
 - Organic compounds


 

 hydrogen and oxygen        