I disagree with the first question. It said, what is the single most important thing you need to survive in the wild, food, water, or warmth. It said water, I disagree.
I think the point is that water is a universal need - whether you're in the sahara or the arctic, you're going to need water. Warmth is only necessary in certain situations, not as "important", for some ill-defined meaning of "important".
If you're trapped in the middle of a zombie infestation, water isn't going to be the most important thing you need to survive, either.
