hi, in option B, im confused with what 'they' refers to. As pronouns can refer to antecedent in previous clauses it can either refer to nuclear plants or 'other plants'. then, it makes this sentence also wrong. please explain

i know that verb +ing modifier preceded with comma and clause modifies the entire clause before it. but, when the preceding clauses has conjunction. does it still modify the preceding clause? like in this case -whereas the electricity they generate is more expensive, stemming from the fixed costs of building nuclear plants.
please explain i'm confused.

mikemcgarry,


Thank you so much for the elaborate post. So, comma, then participle can modify a preceding clause starting with the conjunction. isn't ?

I understand that in A (after the comma) is wrong. But what's wrong with the comparison, can't it be:

While it costs about the same to run nuclear plants as [it costs to run] other types of power plants?

Can someone please explain to me why the pronounce "they" in B has only one antecedent? Can "fixed costs" refer to the antecedent of "they" in the sentence too?

Thank you

I understand that in A (after the comma) is wrong. But what's wrong with the comparison, can't it be:

While it costs about the same to run nuclear plants as [it costs to run] other types of power plants?

Hm, there’s some weird pronoun stuff going on here. The first “it” is a non-referential pronoun: in the phrase “it costs”, “it” doesn’t refer to anything at all. It’s sort of like saying “it is raining” or “it is a bad idea to lick frozen doorknobs.” (I may or may not speak from experience on that last one.)

Non-referential pronouns can be fine, but you don’t see them very often in correct GMAT answers, so they make me nervous.

And of course, there are three of those non-referential pronouns in the sentence! Both “…it is the fixed costs…” and “makes it more expensive” have non-referential versions of “it.” I can’t call them DEFINITE errors, but I don’t love them, and I can’t imagine that a correct GMAT sentence would have THREE non-referential pronouns. Non-referential pronouns just aren’t that awesome, and there’s no good reason to overuse them.

I also see no reason to use “them” toward the end of the sentence: why say “makes it more expensive for them to generate electricity” when you could just shorten it to “makes it more expensive to generate electricity”? Wasted words aren’t cool.

And if you’re not convinced by any of that stuff, there’s a wonderfully serious mistake in (A). “…the fixed costs… makes it more expensive…” That’s a clear subject-verb error.

I’m tired of (A) now. Let’s eliminate it.


I don’t see any major issues in (B). The pronoun “they” jumps out at me, and it seems to refer to the nearest plural, “nuclear plants.” And that works just fine: “the fixed costs that stem from building nuclear plants make the electricity [nuclear plants] generate more expensive.” No problem.

The only other potential objection I see is the comparison at the beginning of the sentence, but… hang on, it’ll be easier to explain WHY that comparison is OK if we put it side-by-side with another answer choice.

So for now, let’s keep (B), and I’ll say more about the comparison at the end of this post.


(C) has a few of the same problems we saw in (A). The subject-verb problem is the biggest issue: “the fixed costs… that makes” is definitely wrong.

We also have a couple of non-referential pronouns in the phrases “it costs about the same” and “it is the fixed costs…” These aren’t WRONG, exactly, but there’s no compelling reason to include them in the sentence unless they somehow clarify the meaning. For more detail, please see the explanation for (A).

But even if you’re OK with the funny non-referential pronouns, the subject-verb thing lets us eliminate (C).


(D) is just plain old confusing. For starters, the pronoun “they” logically needs to refer to “nuclear power plants”, since we know from the context (“stemming from the fixed costs of building nuclear plants”) that the nuclear plants generate more expensive electricity. But “they” is actually closer to “other types of power plants.” That’s confusing – and probably a good enough reason to eliminate (D).

Plus, I still don’t see any good reason to use a non-referential pronoun (“it costs…”) at the beginning of the sentence. See the explanation for (A) for more detail on this.

So (D) is out.

I promised that I’d come back to the comparison in (B), so here it is again, right next to (E):


The comparison error at the beginning of (E) is pretty darned subtle: “the cost of running nuclear plants is about the same as other types of power plants…” Wait, no. We’re trying to compare the COSTS of running the two types of plants, but (E) literally compares the costs of running nuclear plants to the other plants themselves. That doesn’t work.

The version in (B) (“the cost of running nuclear plants is about the same as for other types of power plants”) might not be perfect, but it’s definitely better: the use of the preposition makes it clear that we’re comparing the costs of running nuclear plants with the corresponding costs “for other types of plants.” Fair enough.

You could also argue that the second half of the sentence is clearer in (B) than in (E). (B) is in active voice and more direct: “the fixed costs… make the electricity… more expensive.” (E), on the other hand is passive: “the electricity… is made more expensive because of the fixed costs stemming from building nuclear plants.” (E) isn’t necessarily WRONG in this section, but it’s definitely not as clear and direct as (B).

So (B) is our answer.