Prior to the Industrial Revolution in the Mid-1800s, a Species

Prior to the industrial revolution in the mid-1800s, a species of moth had light-colored wings speckled with small black spots.This coloration camouflaged the moths resting on the birch trees growing in their native habitat, since birch bark has similar coloring.In the early 1900s, this changed as dark soot produced by industrial pollution coated birch trees such that the trees lost their speckled coloring.Years later, it was observed that the moths of this species had changed from being light and speckled to being solid black.Which is the most plausible reason for this change?

A) The moths changed their coloration to match their habitat as a response to increases in birds that preyed on the moths.
B) Black moths migrated into the habitat while speckled moths migrated out to decrease their chances of becoming prey for birds.
C) Birds evolved to become better predators of the speckled moths since there were more of them available as a food source.
D) Both birds and moths evolved to become better able to survive since evolution always causes change in the direction of improving any species.
E) Speckled moths declined and darker variants rose in numbers, as birds could more easily prey on speckled moths and less easily prey on black moths.