Q: You are presented with the quiz "which are required for animal survival?"   But you don't know the answer, so you turn to your teacher to ask for hints. He says that "animals require water for survival" and "hydrogen and oxygen create water".   So, what's the best answer to the question?

pick from the following.
 --hydrogen and oxygen
 --Chemical energy
 --oxygen and methane
 --critical organs
 --sense organs
 --hydrogen and helium
 --light and dark
 --Organic compounds
A:
hydrogen and oxygen