The correct answer is 1, as the first hominid that is believed to have walked upright is the australopithecine.
Australopithecines are an extinct genus of hominid primates. Species of this genus have lived in Africa for just over 3.9 million years until about 2 million years ago. The greatest novelty contributed by australopithecines is that they moved in a bipedal manner. The size of his brain was similar to that of the current great apes.