Biogeography is the study ofA) food preferences of organisms. B) the location of organisms on Earth. C) DNA and RNA nucleotides. D) homologous structures.
The only possible answer to this among the options given to us, is B. Biogeography is the study of how various kinds of organisms are distributed on Earth.
Geography is a field of study that is concerned with the location and distribution of various things. Cultural geography, for example, looks at how cultures vary (or are similar) across space and time. It might ask, for example, how a certain cultural trait (like a religion) was able to spread in the ways that it did.
Biogeography does much the same thing, only with organisms instead of with culture. A biogeographer might ask why a certain type of animal exists in some places but not in others. A biogeographer might look at some endangered species and ask what steps would need to be taken in order to allow that species to spread out and occupy a larger area.
Clearly, these sorts of questions are best summed up by option B.