What Did the Discovery of Neanderthal DNA in Modern Human

What did the discovery of Neanderthal DNA in modern human genomes tell us about gene flow as Homo sapiens emerged from Africa?

A) All of the human variation that exists today was derived from the variation that existed in the population of Homo sapiens that first emerged in Africa; there is no evidence of interbreeding with other hominin populations.
B) Very little human variation is derived from what was present in the population of Homo sapiens that first emerged in Africa; a significant amount of variation was introduced after interbreeding with Neanderthals and Denisovans.
C) Human variation is largely derived from what was present in the population of Homo sapiens that first emerged in Africa, but a limited amount of variation has been passed from Neanderthals and Denisovans through interbreeding after Homo sapiens emerged from Africa.
D) Although DNA extraction techniques continue to improve, there are not enough data to provide conclusive evidence about whether modern humans interbred with Neanderthals.