Final answer:
The correct sentence is A. The trivia question asked for the name of the twenty-first president.
Step-by-step explanation:
The sentence that has correct punctuation is A. The trivia question asked for the name of the twenty-first president. In this sentence, the capitalization, the use of a period at the end of a complete sentence, and the use of hyphens to separate the words in 'twenty-first' are all correct.
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