Which of the following alternative energy sources in not inexhaustible

Assuming that this is referring to the same list of options that was posted before with this question, it is the "sun" that is inexhaustible. Of course technically even the sun will burn out someday, but that won't happen for billions of years. 

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.

The one that would be the most effective means of controlling current water pollution of us surface water is : shutting down factories that discharge materials to the rivers.the largest sum of us pollution currently caused by factory-related substance