Sentence Correction

Many utilities obtain most of their electric power from large coal and nuclear operations at costs that are sometimes two to three times higher as that of power from smaller, more efficient plants that can both make use of waste heat and take advantage of the current abundance of natural gas.

A. two to three times higher as that of power from smaller, more efficient plants that can both
B. higher by two to three times as that from smaller, more efficient plants that both can
C. two to three times higher than those for power from smaller, more efficient plants that can both
D. between two to three times higher as those for power from smaller, more efficient plants that both can
E. between two to three times higher than from smaller, more efficient plants that they can both

Hello Everyone!

Let's tackle this question one problem at a time and narrow it down to the correct answer! After doing a quick scan of the answers, there are a few clear differences between each answer we need to address:

1. Using "as that" versus "than" in a comparison
2. Pronoun-antecedent agreement
3. The use of "between"

First, let's look at the use of "as that" versus "than." These two options are both tied to the comparative word "higher." We know that, whenever we use the comparative, it MUST be followed by the word "than."

The tree will grow higher as that of the roof. --> WRONG
The tree will grow higher than the roof. --> CORRECT

This means we can eliminate answers A, B, and D right away because they all use "higher as" instead of "higher than."

Now we've narrowed it down to just C and E, so let's focus on the differences between them:

C. two to three times higher than those for power from smaller, more efficient plants that can both

This answer is CORRECT because the pronouns and antecedents are clear and in agreement! The pronoun those is clearly referring back to "costs," which is exactly what the GMAT is looking for.

E. between two to three times higher than from smaller, more efficient plants that they can both

Answer E is INCORRECT for a couple reasons. First, saying that the costs are "between two to three times higher" is redundant, which is a big no-no on the GMAT. Second, the pronoun they doesn't make sense where it's placed. It's unclear what they is referring to: the utilities, the power, the costs, etc.? This vague pronoun is another no-no on the GMAT, so this is clearly not the right answer.

That leaves us with C as the correct answer!


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