Choice C is the best answer. The convention being tested is the punctuation of a supplementary element within a sentence. The comma after “sisters” pairs with the comma after “Butterflies” to separate the supplementary element “a fictionalized account of the lives of the Mirabal sisters” from the rest of the sentence. This supplementary element functions to describe the novel In the Time of the Butterflies, and the pair of commas indicates that this element could be removed without affecting the grammatical coherence of the sentence.
Choice A is incorrect because a comma and conjunction can’t be used in this way to separate the supplementary element from the rest of the sentence. Choice B 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 it fails to use appropriate punctuation to separate the supplementary element from the rest of the sentence.