As per option D, the "equations" have done 3 things (depicted by 3 verbs):
1. reduced 2 things (sickness and sleeping on job).
2. lowered fatigue.
3. raised production.

In such construction, please note that the 1st part should be ......reduced sickness AND sleeping on the job. The conjunction "and" is missing between sickness and sleeping in option D. Therefore option D is wrong.

Now for the correct option C:
Shift-work equations have reduced 3 things: 1. sickness, 2.sleeping on job, and 3. fatigue.
However, the equations have increased 1 thing: production
The contrast between increase and decrease is better depicted by the contrast marker "while" rather than "and".

Nonetheless, using "and" could be grammatically correct, if that constructional error mentioned above were not there in option D.

The sentence is in two parallel parts. The first part says "shift-work equations" has 1."reduced sickness", 2. "sleeping on the job",and 3."fatigue.". The second part of the sentence is the result of 1,2, and 3 which is raising production efficiency. Hence raising is the result of these three actions. Hence it should be in " ing " form. The answer therefore cannot be "B" and is "C."
_________________

Aryama Dutta Saikia
Jamboree Education Pvt. Ltd.

To say that this sentence changes the meaning, would be too mild. This sentence is actually not making any sense. This is suggesting that recently implemented "shift-work equations" have reduced four things:

i) sickness
ii) sleeping on the job,
iii) fatigue among shift workers and
iv) production efficiency

The reason this does not make sense, is because if sickness, sleeping, and fatigue are reduced, there is no reason why production efficiency should also reduce.


Absolutely. In fact, our book EducationAisle Sentence Correction Nirvana discusses the parallelism philosophy through a simplified XYZ deconstruct, its application and examples in significant detail. If someone is interested, PM me your email-id, I can mail the corresponding section.
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Thanks,
Ashish
EducationAisle, Bangalore

Sentence Correction Nirvana available on Amazon.in and Flipkart

Now! Preview the entire Grammar Section of Sentence Correction Nirvana at pothi.com

Correct.


Yes.


It's just a list (more than 2 elements), and hence, there is a comma. Another officially correct sentence:

Twenty-two feet long and 10 feet in diameter, the AM-1 is one of the many new satellites that are part of a 15-year effort to subject the interactions of Earth's atmosphere, ocean, and land surfaces to detailed scrutiny from space.

Notice the comma before and land surfaces.

Having said that, the presence or absence of comma before and should not be a reason for you to select/ignore an option.
_________________

Thanks,
Ashish
EducationAisle, Bangalore

Sentence Correction Nirvana available on Amazon.in and Flipkart

Now! Preview the entire Grammar Section of Sentence Correction Nirvana at pothi.com

Consider "while" not as a parallelism marker, but as a contrast marker.

Consider the sentence this way:

Independent clause, present participle modifier (modifying the entire clause preceding it):
Equations have reduced fatigue, (while) raising the efficiency.

Since the modification is to show a contrast, "while" is added before the present participle.

Since this is an official question, it can be inferred that GMAC accepts such use of "while", though I do agree that the sentence you have mentioned is better.

"While" can be used in two ways.

It can be used to start a clause. In such cases "while" is similar to "whereas," and the clause so begun is a subordinate clause.

"While" can also be used to convey, simply, "at the same time", without the connotations of the word "whereas." When used in this way, "while" can be used to begin a clause, but what follows "while" that means "at the same time" does not have to be a clause.

Consider the following examples:

"While" Begins Clause: While the guests were enjoying the sunset, the band set up.

The above sentence conveys that the band set up as the guests were enjoying the sunset.

"While" Without Clause: While setting up, the band members discussed the song list.

This above sentence conveys that, as they were setting up, the band members discussed the song list.

"While Without Clause: My uncle Harry would sing opera while skiing in the Alps.

Notice, in this last sentence, there is no comma before "while". When "while" means "when", you don't need a comma before it. When "while" means "whereas" and begins a clause, the clause has to be separated from the rest of the sentence by a comma.

Here's another example without a comma:

We ran around town while our parents were shopping for bicycles.

The fact that "while" is not preceded by a comma confirms that, in this case, it does not mean "whereas".
_________________

Marty Murray
GMAT Coach
m.w.murray@hotmail.com
http://infinitemindprep.com

That's great
_________________

“The heights by great men reached and kept were not attained in sudden flight but, they while their companions slept, they were toiling upwards in the night.”
― Henry Wadsworth Longfellow

An adverb clause can be reduced to an adverbial phrase if it has the same subject as the main clause.

While I was skiing, I saw ...
is same as
While skiing, I saw ...

It reflects that the two happened "at the same time".


Recently implemented "shift-work equations" ... have reduced A, B, and C while raising production efficiency ...

is same as

Recently implemented "shift-work equations" ... have reduced A, B, and C while they are raising production efficiency ...
_________________

Karishma
Veritas Prep GMAT Instructor

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