GMAT Sentence Correction Workout: The Summative Modifier

Example:

If medical researchers are correct, then the human microbiome, made up of the microorganisms in our body, may hold the cure to diseases that have long plagued humanity, amounting to a major oversight in Western medicine that has, until recently, all but ignored any such role of the microbiome.

Choose the option that best completes the underlined part of the sentence.

A) humanity, amounting to a major oversight in Western medicine that has, until recently, all but
B) humanity, a discovery that amounts to a major oversight in Western medicine, which, until recently, had all but
C) humanity, a discovery amounting to a major oversight by Western medicine: until recently, Western medicine all but
D) humanity, amounting to a major oversight made by Western medicine, one that, until recently, all but
E) humanity, which amounts to a major oversight in Western medicine and until recently it all but

The Summative Modifier

A very subtle point that will come up on the harder GMAT SC questions is the idea of a summative modifier: a word that “encapsulates” the action of the preceding clause.

In order to clearly state what is doing the “amounting”, we use a word that “encapsulates” or captures the preceding phrase. This word is known as a summative modifier.

In other words, it sums up what is being said. The good news here is you do not need to come up with the summative modifier itself, but you will have to find an answer choice that uses one.

Side note: the GMAT will never have multiple possible summative modifiers, asking you to pick the word that best encapsulates the preceding clause.

In this question, “a discovery” is a perfect summative modifier since it captures the idea of the preceding clause:

the microbiome may hold cures to disease, a discovery…

Just like that we can eliminate A), D) and E).

As for B), the “which” refers to the phrase “a major oversight”, since whenever “which” is used, we must make sure that it correctly modifies the subject of the noun phrase that directly precedes it. In this case, the subject of the phrase “a major oversight in Western medicine” is “major oversight”. However, it is not the “major oversight” that is ignoring the role of the microbiome but Western medicine.

C) cleans up this error by clearly stating who has been doing the ignoring: Western medicine.

It may seem that the difference between B) and C) is somewhat similar. Instead of using another summative modifier, which is stylistically off, the correct answer, C), uses a colon and cleans up the error by clearly stating who has been doing the ignoring: Western medicine.

Still unclear what “it” refers to in C)? (Scroll down to the “FAQ” section of the link.)

What the GMAT wants you to know is how to correctly modify clauses and knowing how a summative modifier works will go a long way in your overall GMAT prep. Happy studying!

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  • Chris Lele

    Chris Lele is the Principal Curriculum Manager (and vocabulary wizard) at Magoosh. Chris graduated from UCLA with a BA in Psychology and has 20 years of experience in the test prep industry. He's been quoted as a subject expert in many publications, including US News, GMAC, and Business Because. In his time at Magoosh, Chris has taught countless students how to tackle the GRE, GMAT, SAT, ACT, MCAT (CARS), and LSAT exams with confidence. Some of his students have even gone on to get near-perfect scores. You can find Chris on YouTube, LinkedIn, Twitter and Facebook!