The Atlantic Ocean, formed when Europe split away from America 130 mil

OFFICIAL SOLUTION

A crucial difference between these two structures is the first comma, after the subject. If the subject is followed by a comma, there must be a modifier on the other side of that comma, not a main verb. Here, the subject, the "Atlantic Ocean", is immediately followed by a comma. This is a case in which the punctuation gives us a crucial piece of information about the sentence. We know the overall structure of the sentence must be choice #2 — it cannot be choice #1, because of the presence of that first comma, immediately following the "Atlantic Ocean." The modifiers are participial phrases. Which answer choices follow the "choice #2" pattern?

(A)"The Atlantic Ocean, [participial phrase] "and" [verb], [verb]" = incorrect

(B)"The Atlantic Ocean, [participial phrase] "and" [participial phrase], [verb]" = correct

(C)"The Atlantic Ocean, [participial phrase] "and" [participial phrase], [participial phrase]" = incorrect (missing verb mistake)

(D)"The Atlantic Ocean, [participial phrase] "and" [participial phrase], [verb]" = correct

(E)"The Atlantic Ocean, [participial phrase] "and" [participial phrase], [participial phrase]" = incorrect (missing verb mistake)

Now, we have two possibilities with the correct overall form, choices (B) & (D). Let's look at verb tense. BIG IDEA: verbs or verb forms in parallel do NOT need to be in the same tense. Here, in fact, having the same tense would make absolutely no sense. The first participle, about the formation of the Atlantic, is about something that happened 130 million years ago — since that's not particularly recent, we would need a past participle for that: "formed." The second participle is about something happening "today", so this has to be a present participle: "expanding." Choice (D) illogically makes them the same tense, which leads to a present participle for an event that happened 130 million years ago — sheer nonsense! The only choice that has the correct choice for each participle is choice (B), which is the best answer.