Explanation
Correct answer: C.
Choice C is the best answer. “Finally” logically signals that the bill passing—following many attempts between 1968 and 1983—is the final, concluding event in the sequence described in the previous sentences.
Why the other choices are wrong
Choice A
Choice A is incorrect because “instead” illogically signals that the bill passing is an alternative to one of the events described in the previous sentences. Instead, it is the final event in the sequence.
Choice B
Choice B is incorrect because “likewise” illogically signals that the bill passing is similar to one of the events described in the previous sentences. Instead, it is the final event in the sequence.
Choice D
Choice D is incorrect because “additionally” illogically signals that the bill passing is merely another event described along with the events of the previous sentences. Instead, it is the final, concluding event in the sequence.