Answer:
Natural selection
Step-by-step explanation:
When there was no pollution, the light color of tree bark provided excellent camouflage for the peppered moth, which was predominantly light in color. Some black peppered moths did exist, although they were rare.
During the industrial revolution when there was lots of soot around, the trees became a darker color. This means that now they were a better camouflage for the black moths. As a result, the black moths had a survival advantage, and were much more likely to survive than the lighter colored moths.
As a result, they were more likely to reach reproductive age and pass their genes on to the next generation, leading to an increase in the frequency of black moths. This is an example of natural selection, and illustrates how a species can adapt to its environment,