The sentence that includes parallel structure is C. The car went through the green light, proceeded west on Oak Street, and stopped at the stop sign on Ninth.
In this sentence, each action in the series is expressed in the same grammatical form: "went through," "proceeded," and "stopped." This consistency creates parallel structure, making the sentence grammatically correct and easier to read. The other options either have inconsistent verb forms or do not maintain parallel structure throughout the sentence.