Consider Human Populations Living in Equatorial South America,who Arrived There

Consider human populations living in equatorial South America,who arrived there via North America in a migration that took them from Africa,through Europe,across the Bering Land Bridge into North America,and south to their current location.How,if at all,would skin color have changed over the course of this long migration?

A) Skin color would have been dark in populations migrating out of Africa,lightened as populations were established in northern regions,then darkened again as populations were established in South America.
B) Skin color would have been dark in populations migrating out of Africa.It would not have changed as populations expanded to South America because natural selection would not have had time to select for different skin colors.
C) Skin color would have been dark in populations migrating out of Africa,lightened as populations were established in northern regions,then remained light until populations had been established in South America for at least 10,000 years.
D) Skin color would have been dark in populations migrating out of Africa,remained dark as populations expanded into North America,then become even darker as populations expanded into South America.
E) Skin color would not have changed because the same selection pressures operate in South America than do in Africa.