GMAT Sentence Correction (SC) | Lawmakers who back conservation efforts, which represent a t

Sweet and simple question:

Major split is between have and has. Lawmakers is plural thus we need have. Eliminate B and D.
In C, and keeps subject away from the verb therefore it is not correct.
In Dwith coal being is a marker, so just eliminate this choice. Also it is not one of the acceptable use of being as far as I know.

Lawmakers who back conservation efforts, which represent a threat to the bottom lines of the fossil fuel industry, particularly coal, the nation’s top source of carbon
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