What event in history led to the dark-colored peppered moth being better able to survive than the lighter-colored variety

The smoke from the industrial revolution's factories made it so the trees turned black. The white colored moths couldn't survive anymore because they didn't blend into the trees. One day a genetic mutation happened, and the moth turned dark. The dark moth was able to survive better, and therefore, mated, and produced more dark colored ones. 

The  correct answer should be a waste