The increased popularity and availability of televisions has led to the decline of regional dialects, language variations which originate from diverse ethnic and cultural heritages and perpetuated by geographic isolation.
Option Elimination -
A little bit of basics here. First, we need to understand how the verbals are created. Let's take an example. The person who is speaking on the stage is my friend. So, a shorter way of saying it could be: The person speaking on the stage is my friend. To test which verbal ed/ING will make sense, insert was/were between the modified entity and modifier and see what makes sense. E.g., The broken window needs to be fixed. So, to check, we say "window" was "broken." Also, the "ed" verbals are used in passive. So they have a sense that someone or something was responsible for it. In this case, the was broken by someone or something. It doesn't make sense to say that the breaking window needs to be fixed. We fixed the window after it broke, not while it was breaking.
Take another example - The fascinating book kept me engaged until the end. Let's check. "book" was "fascinating." No one is responsible for me being fascinated by the book. It happens on its own. It's unintentional. It doesn't make sense to say - "book" was "fascinated." The fascinated book kept me engaged until the end. Doesn't make sense.
So if something is unintentional (no one is responsible for it), we use ING verbal, and the opposite of that, if someone/something is responsible, we use "ed" verbal.
So here, what makes sense is "language variations were originating" as its unintentional. No one intentionally originated the variations. Right? So, we use ING. It doesn't make sense to say "language variations were originated." by whom? No one. So, ING is better.
Moreover, in the passive voice, the verb uses the past participle. E.g., The cake was baked by Sarah. We don't say the cake was baking by Sarah. So, for the second part of the sentence, we have to use "perpetuated" here. Something is responsible for perpetuating it. What is that? Geographical isolation.
(A) which originate from diverse ethnic and cultural heritages and perpetuated - "originate" verb and the other side of and we have an ed verbal - not parallel. Wrong.
(B) that originated from diverse ethnic and cultural heritages and perpetuated - "originated" verb and another side of, and we have an ed verbal - not parallel. Wrong.
(C) originated from diverse ethnic and cultural heritages and perpetuated - We need "originating." Perpetuated is ok.
(D) originating from diverse ethnic and cultural heritages and perpetuated - ok
(E) originating from diverse ethnic and cultural heritages and perpetuating - originating is ok. We need "perpetuated."