Answer :
Darker moths thrived in cities because they were able to blend into the trees better as the trees were covered in soot and coal from the factories nearby. The white moths are able to be spotted easier, this contributes to Natural selection by allowing the more successful moths (the darker moths) within the area to at least live long enough reproduce that strand of genes further. Hope this helped. If you have any more questions based on natural selection and/or biology please feel free to message me. Thanks,