Final answer:
A hominid is the common ancestor of humans and apes and is characterized by bipedal locomotion.
Step-by-step explanation:
A hominid refers to the common ancestor of humans and apes. It includes both extinct species and modern humans. Hominids are characterized by their bipedal locomotion, which means they walk on two legs.
For example, early hominids like Australopithecus afarensis, also known as 'Lucy', lived around four million years ago and had a combination of ape-like and human-like characteristics.
Therefore, option D, 'The common ancestor of humans and apes', is the accurate definition of a hominid.
Learn more about Hominids