Liquid water, which is necessary for life as we know it, continues to exist on the surface of Earth because the planet is at a distance, known as the habitable zone, far enough from the Sun that it does not lose its water to the runaway greenhouse effect.
Because all those energy sources are natural and will always be there, when ever there is a need for extra energy.
The correct answer is natural selection. C is the answer!
Bacteria has a stronger resistance that usually produces even more resistant bacteria, and the cycle just repeats itself, making more and more resistant bacteria. This process is called Natural Selection.
Hope that helped!
-Chris
