Dimples is the dominant trait (D). Your friend has dimples so that means he or she should have at least one allele of the dominant trait to express that trait. So your friend would either be homozygous dominant (DD) or heterozygous dominant (Dd). Notice that there is a recessive allele in the second. Even with that present, dimples would be still expressed.
The pollution from the Industrial Revolution darkening the trees. After the trees darkened from all the soot in the air, the white moths were easier to see and more vulnerable to predators. The dark moths blended into the dark tree bark.
