Final answer:
Hominins are B. humans and all extinct species related to humans since the divergence from the last shared ancestor with chimpanzees, characterized by bipedalism and including species like Homo erectus and Neanderthals.
Step-by-step explanation:
Hominins include humans and all extinct species branching from the human lineage after the split from the last common ancestor with chimpanzees. The term hominin refers to species closely related to humans, covering not just modern humans (Homo sapiens) but also extinct human species and our immediate ancestors within the genera Homo, Australopithecus, Paranthropus, and Ardipithecus.
This group is differentiated by various anatomical and behavioral traits, with bipedal locomotion being a key complex specific to hominins. Through the evolutionary journey, several species have evolved after the human lineage diverged from the chimpanzee lineage around 6 million years ago, such as Australopithecus and Homo erectus, as well as our "cousins" like the Neanderthals and Denisovans.