Recently implemented shift-work equations

Ahh...thanks!

Yes, nervousgmat, I chose A.

I tried to make everything parallel. "and have raised" seemed to be parallel with "have reduced"

thought hard between A and C tho.
50% chance and I got it wrong again.

You also need a contrast in this sentence because

reduced W,X,and Y while raising Z

choice C is the only choice that establishes this contrast correctly

Honestly, I feel a bit disadvantaged because I couldn't fathom this question was about BRINGING out the contrast. Grammatically, "have reduced" and "have raised" are perfectly parallel and alright.

I don't deny that C is a more elegant construction - once one has understood the guiding principle - The shift-work equations have reduced X, Y, and Z while raising productivity ..

Raising productivity is active Voice -- while establishes a sense of timing which essentially brings out the contrast -- during the time that fatigue etc were being reduced the productivity was being raised and so on...

I guess with a fair bit of practice alone can these intricacies be understood...

This question actually reminded of the "growth of rail roads led to the abolition of local times DETERMINED by (blah blah) and DIFFERING from city to city etc....

Basically involves establishing parallelism between Past Participle (have reduced) and present participle (raising) ....Not very intuitive but a very powerful concept.

I picked A too..but your explanation is good...thanks..

C.

Parallel parts:
...have reduced noun, noun phrase, and noun phrase while raising

With all these explanations, i am a bit confused between A & C.

What is OA pls..?

A,B, and D all make it sound like the equation was the cause of the improved efficiency.
E 'was lowered' is redundant since 'reduced' has already been mentioned earlier in the sentence.

C is best.