Which choice completes the text so that it conforms to the conventions of Standard English? At eight paragraphs long, the preamble to the constitution of ______blank country in Western Asia-is much longer than the one-paragraph preamble to the United States Constitution.

Choice A is the best answer. The convention being tested is the punctuation of a supplementary element within a sentence. The dash after 'Bahrain' pairs with the dash after 'Asia' to separate the supplementary element 'a country in Western Asia' from the rest of the sentence. Choice B is incorrect because a comma can't be paired with a dash in this way to separate the supplementary element from the rest of the sentence. Choice C is incorrect because it fails to use appropriate punctuation to separate the supplementary element from the rest of the sentence. Choice D is incorrect because a colon can't be paired with a dash in this way to separate the supplementary element from the rest of the sentence.