Answer: D) Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure.
Explanation: parallelism or parallel structure is a literary device that consists in the repetition of the grammatical structure of different words or phrases in a sentence or paragraph, in order to emphasize an idea or to create an impact in the audience. From the given options, the sentence that contains parallel structure is the corresponding to option D, because of the phrase "so conceived and so dedicated."
