What does the out-of-africa model assert?

a. a single origin of modern people and eventual replacement of archaic homo sapiens throughout africa, asia, and europe

b. the importance of gene flow across population boundaries

c. migrations of homo habilis came out of africa

d. migrations of australopithecines came out of africa?

I believe the answer is A. A single origin of modern people and eventual replacement of archaic homo sapiens throughout Africa, Asia and Europe. Out of Africa model; asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus. After Homo erectus migrated out of Africa the different populations became reproductively isolated, evolving independently, and in some cases like the Neanderthals, into separate species. Homo sapiens arose in one place, probably Africa. Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding modern human variation is a relatively recent phenomenon.