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Knewton Challenge Discussion – GMAT Sentence Correction (Peristaltic Pumps)

Posted on October 15, 2010 by

24

This is a Sentence Correction question from SC 3, Extra Practice HW (Parallelism and Comparisons). So far, almost 45% of Knewton students have missed it. How would you approach it?

Try it out, then share your answers, questions, and thought processes in the comments below. Remember, if you’re in our GMAT class now, add your teacher name and session to your comment (e.g., Zwelling, MW 1:30).

In addition to relieving stress and building strength, certain yoga poses instigate the onset of peristaltic pulses in the small intestine, just as peristaltic pumps do, and these have a purgative effect like a laxative’s.

[A] certain yoga poses instigate the onset of peristaltic pulses in the small intestine, just as peristaltic pumps do, and these have a purgative effect like a laxative’s
[B] certain yoga poses instigate the onset of peristaltic pulses in the small intestine, like a peristaltic pump, and they have a purgative effect that is like a laxative
[C] certain yoga poses and peristaltic pumps both instigate the onset of peristaltic pulses in the small intestine, and they have a purgative effect like a laxative
[D] the onset of peristaltic pulses in the small intestine is instigated both by certain yoga poses and peristaltic pumps, and they have a purgative effect like a laxative’s
[E] the onset of peristaltic pulses in the small intestine is instigated by certain yoga poses, just as with peristaltic pumps, and these have a purgative effect like that of a laxative

Posted in Challenge Discussions, GMAT, Verbal Guide | 24 comments



  • EBE

    I’d go with A though not sure about the apostrophe in laxative’s …..

  • Rajiv Bansal

    option A is the answer

  • Anonymous

    e?

    • Rishi4you

      It should be E

  • Saurajm

    A should be the correct one.
    D and E do not directly refer to Yoga but to peristaltic pulses…

  • Dimple

    I think D and E are ruled out because after ‘in addition to relieving stress and building strength’, there should be noun.
    C looks awkward to me.
    Confused between A and B. But in B, they have changes the meaning.
    A seems to be the most appropriate.

  • Jsasipriya

    C, D & E do not convey the intended meaning.
    A is wrong because the idiom is “just as…. so..”
    B is correct.

  • Krishnanthemaverick

    i would go with B if certain yoga is plural else i will go with C.Please help me out guys….am stuck

    • Gmatraju

      how come yoga is plural, yoga is not plural. it is singular

    • http://twitter.com/abhigyan91 Abhigyan Shivaditya

      You said yourself “if yoga is plural”.. you used is in your statement. What does that tell you?

  • Abhishek Ambastha

    A or B, as it should start with ‘certain yoga poses’. Starting of the sentence – In addition … – is talking about yoga poses, so a noun (certain yoga poses) should be there after first ‘comma’.

    Between A and B, A is CORRECT, because of the incorrect use of ‘like’ in choice B. It is not comparing two nouns, so like should not be there!

    Correct Answer: A

  • Kurt

    Correct Answer is B.

    Fist, The modifier that starts the sentence is modifying “certain yoga poses,” so D and E are gone. Second, between A, B, and C, the apostrophe after laxative ruins it for A. So between B and C, C changes the meaning, So I will go with B. 

  • Gaumzisinghal

    IMO B

  • Sree Hari Ragavendra

    B is wrong!!! Certain yoga poses instigate the onset of peristaltic action in the
    small intestine, like a peristaltic pump, and they have a purgative
    effect that is like a laxative – Usage of Like
    is incorrect. We are comparing how yoga poses instigate the onset of
    peristalic pulses with how peristalic pumps instigate the onset of
    peristalic pulses and not the Peristaltic pumps themselves. Eliminate

  • Lilseids

    The answer is A. The “they” in option B is a third person reference, and should be the “these” used in option A as “these” refers to objects.

  • Ranjeet

    Ans should be A

  • A?

    A

  • Anonymous

    Can Knewton reveal the correct answer?

    • http://www.knewton.com Knewton Team

       Just posted it. Thanks for calling our attention to it!

  • Gunjan Sharma

    A

    Reason: use of Just as (Pulses and pump)
                Purgative effects – Both are compared with like — which is correct
                use of Laxative’s

    let me know the official answer please!

  • Jamifahad

    +1 for A.
    A. certain yoga poses instigate the onset of peristaltic pulses in the
    small intestine, just as peristaltic pumps do, and these have a
    purgative effect like a laxative’s

    Use of such as is correct. Yoga poses instigate onset of pulses. Peristaltic pumps instigate onset of pulses too. Hence we use just as with verb at the end to make it a clause to be compared with previous clause.

    Ex:- I will jump up As clowns do.

    Also, purgative effect like a laxative’s (similar to effect of laxative) is correct.

  • http://www.knewton.com Knewton Team

    Here’s the answer, guys. Sorry for the long delay.
    This sentence is correctly written; as peristaltic pumps do is a clause that compares the actions of certain yoga poses to those of peristaltic pumps. Comparative clauses beginning with as must contain a subject and a verb, as they do here. Like is used to compare two nouns, the (purgative) effect of these and the (purgative) effect of a laxative, written in the possessive form a laxative’s. The possessive a laxative’s refers to a laxative’s (purgative) effect, the effect of a laxative. Choice A is correct.

    Note that, though the pronoun these may seem ambiguous, these logically refers to the pulses
    and there are no grammatically acceptable options that are more clear
    than A. All of the other choices contain more than one plural noun or a
    combination of singular and plural nouns to which they or these could refer. Do not be distracted by pronoun usage in this question.

    Choice B: This sentence contains two illogical comparisons. Like must compare nouns; this option seems to compare a peristaltic pump with the closest noun, the small intestine. This is illogical; the sentence intends to compare the actions of yoga poses with those of a peristaltic pump. Like a laxative illogically compares an effect to a laxative. A laxative has a purgative effect, it is not like a purgative effect.

    Option C also compares a purgative effect to a laxative, which is illogical.

    Choices D and E contain a misplaced modifier; the onset… is illogically described by the participial phrase as relieving stress and building strength. 

    The best answer is A.
     

  • Rajesh

    “B” is correct. “Like a peristaltic pump, certain yoga poses instigate the onset of peristaltic pulses”. The stem compares the peristaltic pump with the yoga posses that works like pump. In the “A”, the idiom “Just as” is not followed with the ”so”. Thus it is incorrect.

  • http://twitter.com/darwinl Darwin Ling

    A is the correct answer.

    B is not correct b/c we are comparing between yoga poses and peristatic pumps. They both instigate the onset of peristatic pulses in small intestine

    C is not correct b/c  ”rerelieve stress and building strength” doesn’t apply to peristatic pumps

    D and E are both wrong because the onset of peristatic pulses does not “relieve stress and build strength”