Effective communication is ___________ proves vital in international diplomacy.
Which choice completes the text so that it conforms to the conventions of Standard English?
key for success beyond the borders: negotiating well in crises
key for success, beyond the borders, negotiating well in crises
key for success beyond the borders- negotiating well in crises
key for success beyond the borders; negotiating well in crises,
Correct Answer: A
Choice A is the best answer. The colon correctly introduces an elaboration ("negotiating well in crises") of the preceding independent clause.
Choice B is incorrect because commas are not strong enough to set off this independent elaboration clearly. Choice C is incorrect because a dash is not the standard punctuation for this structure in this context. Choice D is incorrect because the semicolon implies two independent clauses, but the second part is a fragment.