Historical Linguistics Is Defined As

Historical linguistics is defined as:

A) a nonstandard variation of a language that is particular to a specific region.
B) the study of the development of language over time, including its changes and variations.
C) alternating back and forth between more than one linguistic variant depending on the context.
D) the idea that variation in languages appears gradually over distance between places.
E) the study of the intersection between language and systems of power such as race, class, and age.