Final answer:
Mitochondrial DNA analysis is the most direct evidence for determining evolutionary relationships between hominid species, providing a genetic comparison that traces lineage and shows common ancestry, unlike bone density, number of teeth, or geographical location. So the correct option is B.
Step-by-step explanation:
Evidence supporting the idea that an evolutionary relationship exists between two hominid species is best shown by comparing their genetic material. Among the options provided, the best evidence would be (B) Mitochondrial DNA of the species. Analyzing the mitochondrial DNA (mtDNA) allows scientists to determine genetic similarities, trace maternal lineages, and establish evolutionary relationships between species. Studies have revealed, for example, the existence of the Denisovans, a human species or subspecies, through the analysis of mtDNA from teeth and finger bones which showed that they shared a common ancestor with Neanderthals. Genetic sequencing can provide insights into our relationships with other hominids and the degree of interbreeding that occurred among various groups such as modern humans, Neanderthals, and Denisovans.
It's important to note that while other options might provide some information about physiological similarities (like bone density or number of teeth), such traits do not offer as precise information about evolutionary relationships as mitochondrial DNA. The geographical location of a species is also less direct evidence of evolutionary relationships than genetic materials are.