请教OG 128, A and B of C

128. New hardy varieties of rice show promise of producing high yields without the costly requirements of irrigation and application of commercial fertilizer by earlier high-yielding varieties.
(A) requirements of irrigation and application of commercial fertilizer by earlier high-yielding varieties
(B) requirements by earlier high-yielding varieties of application of commercial fertilizer and irrigation
(C) requirements for application of commercial fertilizer and irrigation of earlier high-yielding varieties
(D) application of commercial fertilizer and irrigation that was required by earlier high-yielding varieties
(E) irrigation and application of commercial fertilizer that were required by earlier high-yielding varieties
Answer: E

if "A of B and C" ==> "A of (B and C)" (As the comment in OG, it is ambiguous)

then why "A and B of C" (as in answer E) ==> "A and (B and C)", not "(A and B) and C"

or these alternatives all are right, you have to determine which one by LOGIC??

application of irrigation is meaningful, but irrigation of commercial fertilizer makes no sense. So it's important not only to examine it grammartically but also to examine it semantically.

To be discussed.....

Thanks Tianwan

I agree that in the sturctures such as "A and B of C" and "A and B of C", we need judge them semantically, but in the  OG comment, it says in answer B and D,  "the phase 'application of ... fertilizer and irrigation' is ambiguous in meaning: it can not be clearly determined whether applying fertilizer and irrigating are a single operation or two distinct operations". I just do not understand this explanation.

As my understanding, because the single noun "application" must mean two operations (application and irrigation), and this can be drawn  both grammartically and semantically, and there is no ambiguous in meaning. Why this is a reason for why B and D are not correct, while there are other errors in B and D, such as the structure "Requirement by ... of ..."(should be "Requirment of ... by ...") in B and "was" (should be "were") in D

E use "that were" to clear that the application of fertilizer and irrigation signify 2 distinct processes.

D presents confusing and abiguous meanings

application of commercial fertilizer and (irrigation that was required by earlier high-yielding varieties): manifests 2 different processes and only irrigation is required by earlier high-yielding varietite.

(application of commercial fertilizer and irrigation) that was required by earlier high-yielding varieties: proposes one process required by earlier high-yielding vaireties.

In GMAT, the ambiguity should be eliminated to extent as far as possible.

To be discussed....

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Xie Xie Weiyu

One more thing,

Is it mean if we change "was" in answer D with "were", then D will also be the correct answer??

If so then which is better D or E (I mean change "was" with "were" in D).

I have an idea that shorter one should be in front, so still E is better? or no difference?

改Tianwan: application of commercial fertilizer  is meaningful, but irrigation of commercial fertilizer makes no sense. So it's important not only to examine it grammartically but also to examine it semantically. ( 改了以后更有道理 )