What form of research provides the best evidence of the evolutionary relationship between two hominid species?

documentaries on the development of language in hominids
maps depicting the geographic location of different hominids
articles on the use of tools by hominids
studies in comparative anatomy of different hominids

i know its not b

I would say the answer to this problem would most likely be D because studying the anatomy basically the bone structure would show how similar two creature are or if they mated in anyway shape or form. Also studying the bone structure would reveal all the characteristic they have in common like height tooth size/rigidness, also height, weight and many other important factors.