So we just filmed a
live YouTube webinar on the joys of commas, dashes, colons, and semicolons, and this was one of the questions that we... um, could have covered, but decided not to, because an hour whips by quickly, and we had some better examples. But this particular question has a nice, distracting dash, and much of the webinar emphasized the idea that you don't want to get distracted unnecessarily by punctuation on the GMAT.
And the dash isn't terribly interesting here, anyway. The phrase after the dash is a modifier that tells us more about "antioxidants" -- specifically, everything after the dash is a noun ("compounds") with some modifiers attached to it, and the resulting noun phrase just modifies the noun "antioxidants." It's just that some of the versions of the noun phrase make more sense than others.
And I know that I'm a little bit late to the party (the end of pregnancy is awesome!), but hopefully this will still be useful for a few people!
Quote:
(A) comes from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C that
The most obvious issue here is the subject-verb agreement: the subject "most of the health benefits" is plural, so "comes" is wrong.
The noun phrase after the dash also has a funny flaw. What the heck is the "that" doing there? It seems to modify "vitamin C" only, and that doesn't make any sense: it's the
compounds "that inhibit the formation of plaque", not just the vitamin C.
Either way, (A) is gone.
Quote:
(B) comes from antioxidants—compounds that are also found in beta carotene, vitamin E, and vitamin C, and they
Subject-verb agreement is incorrect again, and that's enough reason to get rid of (B).
Plus, there's really no good reason to end the underlined portion by starting a brand-new clause after the "and." The stuff after the dash is all there as a modifier for "antioxidants", and it's awfully weird to suddenly stick a clause at the end of it. We're much better off if the rest of the sentence just continues to modify "compounds", which is a modifier for "antioxidants."
And even if you don't believe a word I said in that last paragraph, the subject-verb thing is a pretty big deal, so we can ditch (B).
Let's line (C) and (D) up next to each other to make it easier to see which one is better:
Quote:
(C) come from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C, and
(D) come from antioxidants—compounds that are also found in beta carotene, vitamin E, and vitamin C and that
OK, so the subject-verb agreement is fixed here, so the only thing we need to think about is the modifier that comes after the dash. In (D), we have some nice parallelism: "compounds
that are found in beta carotene... and
that inhibit the formation of plaque..." Cool, "compounds" is just modified a couple of times.
But in (C), the end of the sentence is structured in a way that makes it seem like "inhibit" and "found" are verbs: "compounds also
found in beta carotene... and
inhibit the formation of plaque..." That's not cool: we can use the noun phrase beginning with "compounds" as a modifier for the noun "antioxidants" (which is what happens in D), but we can't stick a whole clause in there after the dash as a modifier for "antioxidants" (which is the story in C).
So (C) is out, and we can keep (D).
Quote:
(E) come from antioxidants—compounds also found in beta carotene, vitamin E, and vitamin C, and they
(E) has exactly the same issue as the last part of (B): there's really no good reason to end the underlined portion by starting a brand-new clause after the "and." The stuff after the dash is all there as a modifier for "antioxidants", and it's awfully weird to suddenly stick a clause at the end of it. We're much better off if the rest of the sentence just continues to modify "compounds", which is a modifier for "antioxidants."
(And yes, I cut and pasted some of the text in (B). My wife is in the early bits of labor, so I'm striving for efficiency between contractions. They aren't dramatic yet. TMI? OK, cool. I'll stop now.)
So (D) is the best we can do.