In a small group of people living in a remote area of Kentucky, there is a high incidence of "blue skin" a condition that results from a variation in the structure of hemoglobin. All of the 'blue skinned' residents can trace their ancestry to one couple, who were among the original settlers of the region. The unusually high frequency of 'blue skin' in the area is an example ofa. Mutation b. Natural Selectionc. Sexual Selectiond. Genetic Drifte. Heterozygote Advantage

d. Genetic Drift

Explanation:

Genetic drift, in Biology, is the change of the relative allele frequency of a population that occurs randomly over time. That is, the allele frequency of  the original population becomes changed overtime.

Genetic drift can be said to be caused or favored by several factors, and this could include, small population size, population experiencing bottleneck effect or the founder effect, movement of a gene into a population.

The case of unusual high frequency of "blue skin" that occurred in the small group of people living in the remote area of Kentucky can be said to be an example of genetic drift, as this trait were originated from one couple who migrated as one of the settlers into the region.

the answer would be..

b. sucking