Explanation
Correct answer: D.
Choice D is the best answer. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match.
Why the other choices are wrong
Choice A
Choice A is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match.
Choice B
Choice B is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match.
Choice C
Choice C is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match.