The results— to everyone's surprise were conclusive.
Which choice completes the sentence so that it conforms to the conventions of Standard English?
- — (correct answer)
- ,
- ;
- :
Explanation: This question tests your understanding of how to punctuate interrupting phrases, specifically when dealing with em dashes in pairs. The sentence contains an interrupting phrase "to everyone's surprise" that's set off from the main sentence "The results were conclusive." When you use an em dash to begin an interruption, you must use another em dash to end it. Em dashes work in pairs for interrupting phrases, just like parentheses or commas do. Since the interruption begins with an em dash (after "results"), it must end with an em dash before continuing to the main clause. Choice A (—) is correct because it properly closes the interrupting phrase that began with an em dash, maintaining parallel punctuation structure. Choice B (,) is wrong because you cannot mix punctuation marks when setting off an interrupting phrase. Starting with an em dash and ending with a comma creates an inconsistent, nonstandard construction. Choice C (;) is incorrect because semicolons join two independent clauses or separate complex list items. Here, you're simply ending an interruption within a single sentence, not connecting independent thoughts. Choice D (:) is wrong because colons introduce explanations, lists, or examples that follow. The phrase "to everyone's surprise" isn't introducing anything—it's interrupting the flow of the sentence. Strategy tip: When you see interrupting phrases on the PSAT, check what punctuation starts the interruption. Whatever begins it (em dashes, commas, or parentheses) must also end it. Mixing different punctuation marks for the same interruption is always incorrect.