Explanation
Correct answer: D.
Choice D is the best answer. The convention being tested is the use of punctuation within a sentence. The comma after “village” pairs with the comma after “Under Nushagak Bluff” to separate the supplementary relative clause (“which...village”) from the rest of the sentence. This supplementary relative clause functions to provide additional information about the setting of Heavener’s novel, and the pair of commas indicates that this element could be removed without affecting the grammatical coherence of the sentence.
Why the other choices are wrong
Choice A
Choice A is incorrect because it results in two rhetorically unacceptable sentence fragments, one beginning with “Mia” and the other beginning with “tells.”
Choice B
Choice B is incorrect because it fails to use appropriate punctuation to separate the supplementary relative clause (“which...village”) from the rest of the sentence.
Choice C
Choice C is incorrect because a colon can’t be paired with a comma in this way to separate the supplementary relative clause (“which...village”) from the rest of the sentence. A colon can be used between two main clauses or a main clause and supplement, but here there is no main clause on either side of the colon.