Let me see if I can work this one through....
New theories propose that catastrophic impacts of asteroids and comets may have caused reversals in the Earth’s magnetic field, the onset of ice ages, splitting apart continents
80 million years ago, and great volcanic eruptions.
OK, from the question it looks like this is a parralelism issue. We have a list of things that 'catastrophic impacts of asteroids and comets' may have done, but right now the current underlined sections seems to be out of kilter with the rest of the list. Look at each of the items in turn:
reversals in the Earth’s magnetic field
the onset of ice ages,splitting apart continents 80 million years ago
and great volcanic eruptions.
It is clear that the red section, which equates with the underlined is out of sync. It's the only one with an 'ing' i.e. an action occuring. Everything else is different.
Looking at the answer options gives us a clear winner...
(B) the splitting apart of continents. And here it is by adding the 'the' we change the meaning, and it becomes a statement like the others, rather than something happening.
(C) split apart continents This 'split' is in the past tense - unlike anything else
(D) continents split apart Again past tense
(E) continents that were split apart Once more an action occuring in the past
Hope that helps...
Former GMAT Pill student, now on staff. Used GMATPILL OG 12 and nothing else: 770 (48,48) & 6.0
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