A Key Feature of Language That Helps Explain Anthropologists' Continued

A key feature of language that helps explain anthropologists' continued interest in studying it is that it

A) helps them distinguish between the more and less evolved human races.
B) rarely changes, so it provides a good window into linguistic uses of the past.
C) enables us to compare human and nonhuman primate linguistic grammars.
D) is always changing.
E) tells us a lot about the present, although nothing about the past.