Starfish, with anywhere from five to eight arms, have a strong regener

So there’s an interesting thing in this question: “starfish” could, in theory, be either singular or plural. (Much like the word “media” or “data” or “deer” or diabetes.) The GMAT has a very consistent habit in these cases: the sentence will always give you some other indication of whether the word is singular or plural.

And in this case? In the non-underlined portion, we have the phrase “Starfish... have a strong regenerative capacity...” So “starfish” is definitely plural, at least in the beginning of the sentence. (And yes, this explanation has been edited to correct my original error. File under: even ninjas write dumb things in the wee hours of the morning.)

Hopefully, the word “it” leaps off the page at you immediately – both of them. Logically, we know that the first “it” needs to refer back to “starfish”, and the second “it” refers back to “arm.” But in its current form, it’s awfully confusing: “it” appears twice in close succession, but the two pronouns refer back to different things? That’s not cool.

And more importantly, “it” can’t refer back to “starfish” anyway, since the beginning of the sentence indicates that “starfish” is plural.

Plus, the meaning of the last part of the underlined portion is funky: the phrase “by the animal overcompensating” suggests that the overcompensation is how the starfish replaces its arm. And that doesn’t actually make sense.

Either way, we can do better than (A).

OK, this “it” looks much better. The word “arm” is the closest potential referent to “it”, so we’re OK here: “... if one arm is lost [the arm] is quickly replaced...” Cool.

I don’t love the use of “with” here, but I can’t see why it’s wrong, exactly. And the meaning makes sense: sometimes, the animal overcompensates and grows an extra arm. That’s kind of creepy from a biological standpoint, but perfectly OK grammatically. “Overcompensating” and “growing” are two parallel actions that are sometimes taken by the animal – and I see no reason why the two actions can’t be parallel.

Let’s keep (B).

The pronouns aren’t horrible here: “it” clearly refers to the arm and “they” presumably refers to starfish. But I think you could make a case that there MIGHT be a pronoun ambiguity issue with “they”, since “arms” is actually the plural noun that’s closest to the pronoun “they.” This isn’t an automatic elimination, since pronoun ambiguity isn’t an absolute rule on the GMAT, but it’s something you should always notice. (More on pronoun ambiguity in this YouTube video.)

But here’s the really important part: the use of “by the animal overcompensating” still doesn’t make any sense (see answer choice A above). The starfish doesn’t replace the arm by overcompensating; it just happens to overcompensate sometimes and grow an extra arm.

Because of the meaning issue, (C) can be eliminated.

Again, we could argue that the first “they” isn’t automatically wrong, even though it’s potentially ambiguous – “they” could again refer to “arms” or “starfish.” But the second “they” is absolute nonsense, since “arm” is a singular noun in this particular chunk of the sentence. So (D) is gone, too.

This is awfully tempting, and I don’t think that there are any DEFINITE reasons to prefer (E) over (B). But there are a bunch of things that make (B) very, very slightly better.

Let’s line this one up with (B) to make it easier to compare them:


So we have three meaningful differences here, and none of them are smoking guns, but all of them seem to point in the same direction.

In that first chunk of the sentence, the big difference is that (E) uses the pronoun “they”, which is potentially ambiguous, since it could refer back to “starfish” or “arms” – and since “arms” is the most recent plural, you could argue that “they” is a legit problem here. Honestly, I’m not completely convinced by this – there are plenty of official SC questions with similar ambiguities in the correct answers. But in this case, the pronoun issue gives me a very slight preference for (B).

Second, we have some funny business with the placement of the word “sometimes.” The thing that “sometimes” happens is “overcompensating”, so it makes sense to have “sometimes” right next to that word. Is it totally wrong to say “sometimes with the animal overcompensating”? Nope. But again, I’d have a very slight preference for (B) based on the placement of “sometimes.”

And the third thing? In (B), “overcompensating” and “growing” are two parallel actions. In other words, the animal sometimes does two things: it overcompensates and grows an extra arm or two. That makes enough sense. In (E), “growing” has been turned into a modifier (“sometimes with the animal overcompensating, growing an extra arm or two”), and I’m not sure that it’s wrong, but it seems a little bit odd to me: when do you ever see an "-ing" participle modifying another "-ing" participle? Meaning-wise, I suppose you could argue that “growing” tells us extra information about when happens when the animal is “overcompensating”, but I think it makes more sense to keep the two actions (“growing” and “overcompensating”) parallel.

Honestly, I don’t think that any of these three issues are crystal-clear, slam-dunk reasons to eliminate (E). If I were seeing this question on an actual exam for the very first time, I’d say a quick prayer to the GMAT gods before picking (B) and moving on -- but at least I'd be comforted by the notion that all three of those little issues point in half-assed unison toward (B).