Which of the following is an example of human genetic mutation and selection resulting from the Neolithic Revolution? a The permanent "switch-on" of the lactase gene, prevalent in some populations, which allows humans to digest milk beyond weaning from breastmilk. b The grain-induced increased expression of the HMGA2 gene, resulting in a variance of height between modern Greeks (taller) and their foraging ancestors (shorter). c The Y−5 tooth pattern that enables modern humans to chew grains. d The decrease in melanin in some populations living in northern latitudes, resulting in a high frequency of blue or green eyes and blonde or red hair.