Official Explanation
Tactical Analysis:
Since option D looks so different from the other four, start off by reading the sentence with that option plugged in. You should find that D doesn’t work because the modifying phrase “From 1861 to 1865” isn’t in the right place – it should be after the Civil War, not before it. Therefore, we can quickly rule this one out.
By quickly looking at each option that’s left, we see that in A, B, C, and E, the main difference is what comes after the comma. Focus on the verbs here: taking/took/takes/has taken. If we’re talking about an event that happened in the past, and isn’t still going on today, which verb tense works best? Past tense. We know that the past tense of “to take” is “took,” so there’s your answer!
B is the right answer, and here’s a breakdown of specifically why the other answers are wrong:
A is incorrect because it uses the present tense gerund “taking place” instead of past tense “took place.” Since we know the Civil War took place in the 1860s, it doesn’t make sense to use present tense.
B is correct because it uses the proper verb form, and the modifier phrase is in the right place.
C is incorrect because, like answer A, it uses a present tense verb “takes place” instead of past tense. The Civil War isn’t still going on, so it’s best to use past tense.
D is incorrect because the modifier “From 1861 to 1865” doesn’t clearly fit where it’s placed. It kind of suggests that the Civil War lasted longer, but that we’re only discussing what happened between 1861-1865.
E is incorrect because it changed “which” to “that,” which changes the meaning a little bit. By using “that,” we’re saying there was more than one American Civil War, and that we’re talking about the one that happened between 1861-1865 specifically. It also uses the present perfect “that has taken place,” which also assumes the war only recently ended, which isn’t true.