A 3 min read

In this article, we’ll look at the solution to this GMAT Official guide sentence correction question – To help preserve ancient Egyptian monuments threatened by high water tables, a Swedish engineering firm has proposed installing pumps, perhaps solar powered, to lower the underground water level and dig trenches around the base of the stone walls.

We have analyzed the 5 answer choices and arrived at the correct choice through 3 steps:

1. Meaning analysis
2. Error analysis
3. Answer choice analysis

General information on GMAT OG SC question

1.1 Question – To help preserve ancient Egyptian monuments threatened by…

To help preserve ancient Egyptian monuments threatened by high water tables, a Swedish engineering firm has proposed installing pumps, perhaps solar powered, to lower the underground water level and dig trenches around the base of the stone walls.

[Refer to the GMAT Official Guide for options]

1.2 Meaning Analysis

1.2.1 Sentence Structure

1.2.2     Meaning

The sentence discusses the problem of rising water levels threatening ancient Egyptian monuments. The way the sentence is structured, the meaning is not clear. The original sentence indicates that a firm has proposed installing pumps, and the intent is for the pumps to lower water and dig trenches. However, we know it is illogical to state that a pump intends to dig a trench. Thus, we must infer the logical meaning that a Swedish engineering firm has suggested two things: installing pumps that possibly will be solar powered to lower the level of underground water. The second idea is digging trenches around the bottom of the stone walls.

1.3 Error Analysis

1. Parallelism Error: The list in this sentence — “to lower…” and “(to) dig…” — are grammatically parallel but not logically parallel. Through meaning analysis, we understand that the suggestions must be in proper parallel structure “installing pumps” and “digging trenches.”

1.4 Answer Choice Analysis  

A: to lower the underground water level and dig trenches

Incorrect: Error as discussed in the error analysis

B. to lower the underground water level and to dig trenches

Incorrect: Parallelism Error leading to Meaning Error: This choice repeats the error of the original sentence. The only between this choice and Choice A is that this choice explicitly mentions “to” before “dig” to make the list obvious. But this list is illogical.

C. to lower the underground water level and digging trenches

Correct: This option corrects the error in the original sentence. The two suggestions – “installing” and “digging” – are now grammatically and logically parallel. 

D. that lower the underground water level and that trenches be dug

Incorrect:

1. Modifier Errors leading to Meaning Error
   • The removal of the “to + verb” phrase changes the meaning by removing the purpose of the pump to lower the underground water level.
   • The addition of “that” to this option makes the two “that” clauses parallel. Since the first clause modifies “pumps,” the second clause should also modify pumps since the two are joined by “and”. However, this modification is illogical.
2. Verb Error: The verb “be dug” is a subjunctive verb. This usage is incorrect because there is no trigger word that requires the usage of the subjunctive verb.
3. that lower the underground water level and trench digging:

E. that lower the underground water level and trench digging

Incorrect:

1. Parallelism Error:  This option does not offer the needed parallel structure “installing pumps” and “digging trenches.”
2. Modifier Error leading to Meaning Error: This choice repeats the error of Choice D with regards to the use of “that”.  

1.5 Takeaways

1. Meaning is paramount. Always make sure you take the time to analyze the intended logical meaning. The intended meaning may be different than what the original sentence structure communicates.
2. Do not be afraid to select a choice that uses a different sentence structure if it correctly communicates the author’s intended logical meaning.
3. Parallel entities must be logically and grammatically parallel.

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