Answer:
a. Australopithecine Afarensis
Step-by-step explanation:
With a skull of 3 million years, scientists have been able to prove the existence of Australopithecus afarensis, the oldest ancestor of humanity. 4 million years ago, humanity did not exist. But at least one creature bore in its bones what would be the hallmark of Homo sapiens. Australopithecus afarensis, that creature's name, had a tiny brain. But it stood like no monkey could do, representing an ancestral trait that would be passed from generation to generation to modern man.