OFFICIAL EXPLANATIONWe are halfway through the competition now. How are you faring? By this point, you have faced some quite tricky questions, while others have proved more manageable (according to the timer data). I would like to think that with each OE I write, you may be getting one step closer to perfection on the Verbal end of the GMAT™. Just stick with it. Persistence pays off.
Quote:
The new technology employs light detection and ranging (LIDAR), using lasers from satellites to measure distances to Earth and generate highly accurate topographical maps for researchers to assess likely volcanic floodplains.
(A) to measure distances to Earth and generate highly accurate topographical maps for researchers to assess likely volcanic floodplains.
There are a few talking points here, but everything checks out. The adverbial
to measure is simply a shortened form of
in order to measure, and
generate builds from the same understood
to. Depending on the gap between the beginning of parts X and Y in this sort of
and construct, you may see a word such as
to repeated in front of the second element, but there is no definite rule (e.g., one based on word count) on when that needs to occur. Finally, the placement of the word
likely allows us to appreciate that researchers can use these maps to check for probable volcanic floodplains (perhaps without having to risk life and limb by traveling to such locations). There is nothing that stands out as incorrect, so keep this one.
Quote:
(B) that measure distances to Earth and generate highly accurate topographical maps of volcanic floodplains for researchers to likely assess.
First off, notice that
to has been swapped out for
that at the head of the underlined portion. Although the nature of the clause is somewhat different from that of the earlier phrase, there is nothing inherently wrong with saying
lasers from satellites that measure distances to Earth. In any case, I would not eliminate the answer choice on such grounds. The latter portion runs into trouble, though, when it comes to the meaning conveyed, and this meaning hinges on where
likely falls. Whereas before, the maps helped researchers identify
possible volcanic floodplains, now the maps are definitely of those floodplains, and, worse yet,
likely assess makes it sound as if the maps are being generated for some unknown purpose, that maybe researchers will get around to checking out all these highly accurate maps, but maybe not. Even though there is nothing grammatically wrong with the sentence, the meaning is certainly not as clear as what was expressed in the original sentence, so I would discard this answer choice in favor of (A).
Quote:
(C) for likely measuring distances to Earth and generating highly accurate topographical maps of volcanic floodplains for researchers to assess.
This
likely keeps bouncing around and wreaking havoc on the meaning of the sentence. Now the nature of the satellites is more or less a complete mystery, the information pertaining to them speculative. Why, then, do we get this description about how the satellites work and what they apparently do? Something seems off when the sentence is considered as a whole. Also, even though
measuring and
generating are parallel, there is no compelling reason to opt out of our adverbial
to phrase for this prepositional
for phrase—
using lasers to measure is the grown-up version of
using lasers for measuring. This should be another easy elimination.
Quote:
(D) to measure distances to Earth and likely generate highly accurate topographical maps to researchers to assess volcanic floodplains.
This version is a little
to happy. But first, we once again have a problem with
likely. This time, the measuring can be taken as fact, but the generating of maps is uncertain. Getting back to
to,
generate maps to researchers could work in a certain context, perhaps if the sentence wrapped up,
on their mobile devices. We might picture a sentence that was outlining a process about the transmission of data. But in this sentence,
maps to researchers to assess is difficult to follow; the preposition
for is warranted:
maps for researchers to assess. Since this is another subpar version of (A), we should feel comfortable tossing it aside.
Quote:
(E) that measure distances to Earth and generate highly accurate topographical maps for researchers likely to assess volcanic floodplains.
Again, this one is fine grammatically. But now we are pigeonholing the type of researchers for whom these maps are generated. Evidently, not just any researchers can gain access to these maps, only those who are
likely to assess volcanic floodplains. Do the satellites generate
other types of maps for different researchers, perhaps less accurate maps? This is a subtle change of meaning, but if we have reason to doubt the sentence, we should not merely close our eyes and hope for the best. SC is about seeking to attack each of the five options, and clarity of meaning should be your primary concern. This iteration just misses the mark.
I hope that helps. I would be happy to answer any follow-up questions. Good luck with the challenges that lie ahead.
- Andrew
close
19 Dec 2020, 07:00
45%
(medium)
32%
(02:01)
wrong 
) is doing the measurement. 
