A is correct answer. ....
This is because in the "U.S.A.", people in all the regions in the U.S.A. historically migrated throughout an "entire land mass" (essentially) ; and this "land mass" tends to be more "homogeneous" (as opposed to "British English" speakers; who speak with different dialects, accents). Note that the United Kingdom, including Great Britain, is further isolated from the U.S.A.—by a huge ocean— than the "relatively more homogeneous physical region"/ and thus the "relatively more linguistic region".
Answer:
B. Optional
Explanation:
A comma can be defined as a punctuation mark that is typically used for indicating a break in elements of a series or list in a sentence. Also, it's used to indicate the shortest pause in a sentence.
In the English language, conjunction can be defined as an English word that is typically used for connecting two or more clauses, words, phrases, or sentences. Some examples of conjunction are but, and, although, because, or, yet, etc.
When there are three or more items (elements) in a series, the final comma before the conjunction (and, or, nor) is optional.
