During the industrial revolution in England, a population of light-colored moths population fell while a population of dark-colored moths population rose. Both types of moths were usually found on the trunks of trees in cities.

Apparently, birds were eating the light-colored moths at a faster rate than they could reproduce. But they were leaving many of the dark-colored moths alone. What is the BEST explanation for this data?

a
The trees had become coated with soot and the dark moths were better camouflaged.
b
Dark-colored moths flew faster than light-colored moths.
c
The birds' vision had become impaired.
d
The white moths had become tastier.