The answer is D. Just think how hard it would be to see a moth of that colour when just about everything during that time period is grey.
Let's look BB and Bb
They both have the dominant trait which means they both have the same physical appearance (phenotype) , but while BB has both dominant and Bb has one dominant and one recessive that means that although Bb has the same phenotype as BB, it has a different genotype because it has a bit different genetic makeup
Tectonic plates, is probably the answer