The Nobel Prize in chemistry was awarded to three scientists for their

So you might be wondering: why the heck did we pick THIS thing for a QOTD?

Well, we just finished a big ol' live webinar on the joys of commas, dashes, colons, and semicolons. We didn't cover this particular question, but here's the big takeaway from the webinar: dashes aren't usually worth worrying about on the GMAT, because they're rarely the deciding factor in a question -- and style experts disagree about the exact uses of dashes, anyway.

So on something like this question, don't get too distracted by the dashes, and concentrate on finding other goodies if at all possible.

I can’t complain much about (A). The first phrase beginning with "that" is very reasonably modifying the preceding noun ("...discovery that plastic can be made electrically conductive..."), and the second "that" is fine, too ("... an advance that has led to improvements..."). Might as well keep (A).

And in case you ARE worried about how dashes work: in this case, everything that follows the dash is a modifier -- specifically, a noun that modifies another noun -- that tells us more about the "discovery that plastic can be made electrically conductive." That's no problem at all, since the phrase after the dash ("an advance that has led to improvements...") is a perfectly reasonable definition of the discovery.

(And plastic can be made electrically conductive?! Mind. Blown.)

Anyway, let’s keep (A).


I don't think that (B) is WRONG, exactly, but it's far less elegant than (A). The only real difference between (A) and (B) isn't the dash itself; it's the stuff that follows the dash, which is intended as a modifier that tells us more about "their discovery." I think it's easier to see the problem if we put (A) and (B) side-by-side:

(A) ... the discovery that plastic can be made electrically conductive—an advance that has led to improvements...
(B) ... the discovery that plastic can be made electrically conductive—this advance leading to improvements...

Again, the part after the dash is just trying to give us a nice, clear description of “the discovery.” (A) does this much more elegantly, by giving us a definition of “the discovery”: it’s “an advance that has led to improvements…” Structurally, it’s harder to make sense of (B): I might be OK with just “leading” instead of “this advance leading” (especially if we tweaked the punctuation), but I can’t figure out why we would have a noun (“this advance”) followed by a participle (“leading”) in this situation. (Or in any situation, to be honest.)

It’s subtle, but (B) is definitely weaker than (A).

(C) isn’t horrible, but it’s not great, either – especially when we compare it to (A). In (A), the stuff after the dash is clearly just a modifier that tells us more about “the discovery.” But in (C), the phrase beginning with “and this advance led…” is structured as a brand-new clause, parallel to the first (independent) clause in the sentence.

In this situation, we have to ask ourselves: which is more appropriate? Are we trying to state two separate, independent, parallel facts (which is what A does)? Or should the last part (beginning with “an advance” or “this advance”) just modify “the discovery”? I’d argue strongly for the latter: there’s absolutely no reason to start up a brand-new, parallel clause in this case, when you think about the meaning of the sentence.

So it’s still pretty subtle, but (C) isn’t as good as (A), either.

There are two little problems with (D). First, it’s awfully weird to talk about “the discovery of plastic’s ability” in this case. Literally, that sentence suggests that plastic inherently has the ability to be electrically conductive, and scientists just happened to discover that inherent ability. And that doesn’t make sense: what we’re really trying to say is that plastic can be made electrically conductive – presumably with some modifications or whatever.

Second, this seems like a classic, crappy use of “with.” The word “with” suggests some sort of accompaniment (“I eat burritos with Tapatio sauce” or “Mike went to the movies with his non-girlfriend”), and I can’t figure out why we would use “with” here. Especially since we have a much clearer alternative in answer choice (A), that gives us a very clear modifier that gives us more information about “the discovery”.

So (D) isn’t a total disaster, but it’s also inferior to (A).

Let’s line up (A) and (E) side-by-side, since they aren’t all that different from each other:

That first part of the underlined portion in (E) is pretty ugly. At the very least, it’s far less elegant than (A), and there’s no good reason to use the phrase “being able to be made” when we could just use “can be made.”

But I think there’s also a meaning argument here, similar to the argument I made for eliminating (D): the phrase “discovery of plastic being able to be made…” sounds like scientists either just discovered plastic itself, or just discovered plastic’s inherent ability to be electrically conductive. And that’s not quite right: scientists just discovered that plastic can be made electrically conductive – again, perhaps with some innovative modifications. But (E) seems to suggest that plastic inherently can be made conductive, and that doesn’t work.

So (A) is the best we can do.