ildude02, I will go for C. To me, it can not be A because, the sentence is already having HAVE as its verb (to indicate present perfect tense) - so no need to have one more HAVE in the underlined section. B in that case comes next to select. But if u refer C, it is saying clearly that two opposing actions go on here. One is reducing all those negative effects while increasing the positive effect. So it is coming as the best option to chose. Are u getting me ildude02?

Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, FATIGUE AMONG SHIFT WORKERS, AND HAVE RAISED production efficiency in various industries.

In its present form, the sentence is no good because it lists 4 items but the modifier "have reduced" is only supposed to apply to the first 3 items. However, since "have reduced" appears only in front of the first item, by implication it goes in front of all 4. We need to break the list up into two sections to avoid the trouble.

We want the first part of the list to read:

"have reduced sickness, sleeping on the job and fatigue among shift workers"

and only answers (c) and (d) have the "and" that we require.

(d), however, introduces another problem. Putting the word "reduced" in front of the 3rd item in the list is redundant, since we already have "have reduced" in front of the 1st item in the list.

Therefore, choose answer (c). The connector "while" indicates that the next part of the sentence is somehow different from what we previously read, which is exactly what the author wants to convey.

In simplified form (a great way of checking answers), (c) reads:

Recently implemented equations have reduced a, b and c while raising d.

Sounds great!

Thanks for your eplanation guys.

I happen to choose choice (a) since I got locked into the "parallel" structure between "have reduced" and "have raised". Since both of them are having parallel structures with respect to the "have", I felt the sentence is fine as it stands.

If possible, can any of you guys explain how do I make sure that I apply or not apply parallelism. Especially if there is sentence with many parts and lengthy modifiers, how to make sure which part of the sentence or modifers should I look out for parellelism and not get tangled with the parellism of the "not so important" modifiers. I'd appreciate your thoughts.

Stuart Kovinsky wrote:
In its present form, the sentence is no good because it lists 4 items but the modifier "have reduced" is only supposed to apply to the first 3 items.

Stuart can you please explain why do you say that have reduced is only supposed to apply to the first 3 items, is that a rule or is that implied in the sentence.

Thanks,

Vineet

vineetbatra wrote:

Stuart Kovinsky wrote:
In its present form, the sentence is no good because it lists 4 items but the modifier "have reduced" is only supposed to apply to the first 3 items.

Stuart can you please explain why do you say that have reduced is only supposed to apply to the first 3 items, is that a rule or is that implied in the sentence.

Thanks,

Vineet

That's just this particular sentence - the "and have raised" before the 4th item in the list clearly indicates that production efficiency wasn't reduced.

While it's rare, it's perfectly OK to have 4 items in a list (for some reason, we almost always only have 3 items in lists). For example, it would be both grammatically and stylistically correct to say:

Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, FATIGUE AMONG SHIFT WORKERS, AND production efficiency in various industries.

@Stuart
your explanation is awesome.
My doubt is we can say that in option A, 3 items -sickness, sleeping and fatigue are parallel and "HAVE RAISED production efficiency" is another clause. Now why this clause needs to be parallel to first 3 items?

vaibhav.iit2002 wrote:@Stuart
your explanation is awesome.
My doubt is we can say that in option A, 3 items -sickness, sleeping and fatigue are parallel and "HAVE RAISED production efficiency" is another clause. Now why this clause needs to be parallel to first 3 items?

Well, the general answer is we want all elements of a sentence to be parallel.

However, the bigger problem with the original is that if we view it as 2 different ideas (our list of 3 items + 1 different item), there's no "and" in the first list. We just have "have reduced sickness, sleeping on the job, fatigue among shift workers"; for that to be a proper list in its own right, it needs to read:

"have reduced sickness, sleeping on the job AND fatigue among shift workers".

@Stuart
Got it
Thanks

I am still confused on the correct answer choice E because the "while raising" throws me off.

In a nutshell the sentance reads: Recently implemented equations have reduced X, Y, and Z while raising A.

How is "raising" a correct tense when the sentence is in present perfect?
Is it also correct to say" "shift work equations" have reduced X,Y, and Z and have raised A.
Does "while" introduce an adjective clause? If so, what does "while" refer back to? I thought that the "while" modified that entire prior clause before which is why I thought it was wrong.
Would the sentence be wrong if it had a comma before the "while"?

stuart,

thanks for your insight on this...Pl. calrify this.

If the original sentence were "Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, and fatigue among shift workers and have raised production efficiency in various industries. " , would you change it over option C.

look forward to your response.

ansumania wrote:stuart,

thanks for your insight on this...Pl. calrify this.

If the original sentence were "Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, and fatigue among shift workers and have raised production efficiency in various industries. " , would you change it over option C.

look forward to your response.

Your variation is grammatically correct, but uses an extra word, so I'd still stick with C.

However, here's the good news: your variation and C are way too close to both appear as answer choices; on the actual GMAT you'd never have to make such a tough choice. If your variation appeared on the test, C wouldn't.

cwbeemer wrote:I am still confused on the correct answer choice E because the "while raising" throws me off.

In a nutshell the sentance reads: Recently implemented equations have reduced X, Y, and Z while raising A.

How is "raising" a correct tense when the sentence is in present perfect?
Is it also correct to say" "shift work equations" have reduced X,Y, and Z and have raised A.
Does "while" introduce an adjective clause? If so, what does "while" refer back to? I thought that the "while" modified that entire prior clause before which is why I thought it was wrong.
Would the sentence be wrong if it had a comma before the "while"?

Any thoughts anyone?