This question is fairly straightforward. When we look at the answer choices, B and D just don’t even sound right, so it is probably safe to eliminate them. They both create appositives, which are words like this in between two commas, which can be completely removed from a sentence with the commas and the sentence will still be grammatically correct (read that sentence again but without “, which are words like this in between two commas,” to understand). So now that those two are out, we can look at choices A and C. A also creates an appositive, but that may be hard to catch because the second comma is outside of the part of the sentence being changed. If we didn’t change the sentence, it would make “for films such as Selma (2014)” an appositive, and we can’t remove this part of the sentence without the rest of the sentence making no sense. Now that we have eliminated A, we know that the answer is C.