Flocks of birds and schools of fish instinctively use highly-coordinat

Hello, aritrar4. The problem with using the infinitive in the sentence at hand is that you cannot negotiate the comma before the underlined portion. Remove that comma, and (E) would be correct: X and Y use highly-coordinated wavelike movement [in order] to protect themselves... Choice (D) serves in the same explanatory (adverbial) capacity, and, more importantly, the -ing phrase works with the comma to modify the preceding clause. You can almost picture a ghost thereby at the head of the phrase: X and Y use highly-coordinated wavelike movement, [thereby] protecting themselves... The comma here makes all the difference.

I hope that helps clarify the issue. If not, feel free to ask for additional help. Thank you for calling my attention to the question.

- Andrew
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Hi guys,

A simple participial modifier works best in this construction!

A) A noun modifier, Appositive phrase, will not be appropriate in this construction. Since, the appositive phrase modifies the noun it is attached to; in this case, the wavelike movement. But the focus of this question is to highlight how birds and fish 'instinctively use' the wavelike movement. So, we need an adverbial, which is provided by the participial modifier in option D.

B)Option B can be eliminated for the same reasons as in option A. Further, the construction is awkward. The comma is unnecessary.

C)The comma is unnecessary. Further, 'as' is a conjunction and must be followed by a clause to compare with the previous clause. Here, 'as' is followed by a noun phrase which is inappropriate.

E)The infinitive is inappropriately placed. The infinitive modifies wavelike movement whereas we need to highlight the verb instinctively use

Option D uses the most appropriate method,the participial modifier, to modify the verb instinctively use and is superior to all the other options. Hence D.

Whats wrong with A ?
Can't it act as a noun modifier ?

Also, the meaning difference between Option D and option E is subtle. Option E suggests that the two actions ,use of movements and protecting, occur in a sequence, separately. However, if we check the construction of the sentence, it suggests that the use of movements and the protecting occurred simultaneously . The protecting occurred as an accompanying circumstance, like a circumstance adverbial. The infinitive in option E suggests sequential action which is not the intended meaning. Hence, option D with its participle suggesting a simultaneous occurrence of the two actions is correct

OE

Read the Original Sentence Carefully, Looking for Errors:

The underlined portion seems like a wordy way to begin explaining the purpose of the wavelike movement. It is also not correct with the reflexive "themselves." The underlined portion needs to contain an action that applies to the subjects—the birds and fish. "A method" does not do this. Expect the correct answer to introduce the rest of the explanation more concisely and to fit with "themselves."

Scan and Group the Answer Choices:

A quick scan of the choices doesn't reveal any patterns that can be used for a useful grouping. Fortunately, the choices are short, so analyzing each one will not take long.

Eliminate Wrong Answer Choices:

(B) is as wordy as (A) and doesn't improve upon it in any way. Eliminate (B).

(C)'s "as a protection of themselves against predators" is unidiomatic. Creatures may protect themselves, or use protection against predators, or obtain protection from predators. But it is simply not said that creatures do something as a protection of. Eliminate (C).

(E) may be tempting, and it would indeed be correct if there were no comma after "movement." It would have made sense to say, "use highly coordinated wavelike movement to protect themselves...." But with the comma, "to protect" doesn't fit in. (E) must be eliminated.

(D) is a concise, direct improvement on the wordy original. When the creatures use the wavelike movement, they are "protecting themselves against predators...." A similar, simpler example of this construction is People carry umbrellas, protecting themselves against rain. (D) is correct.

TAKEAWAY: Although punctuation is not explicitly tested in Sentence Correction, it can come into play when determining the best wording. The best way to deal with a sentence that tests wording in this way is to read the choices back into the sentence, being sure to note the punctuation marks.

daagh, AndrewN Could you please help me with this sentence? Since infinitives define purpose, so should the coordinated movement of the birds and fishes be followed by "to protect" rather than "protecting" which signifies does not signify that they are protected as a result of their coordinated movement.

Thanks for your help !

Thank you AndrewN, I'd missed the comma again...

Agree a N+NM would fit in more here
verb-ing would modify "wave-like movement"
egmat could you please opine?

Hi, can you explain why A is wrong?
I think both A and D are correct.

Please tell us why A or E is wrong

Flocks of birds and schools of fish instinctively use highly-coordinated wavelike movement, a method to protect themselves against predators that would much rather attack an individual member that strays from the group.

A) a method to protect Incorrect

it could be correct if that is used - a method that protect themselves, than it could be uses as noun modifier

B) as a method protecting Incorrect

as a method uses wrong as modifier

C) as a protection of Incorrect

as a protection uses wrong as modifier

D) protecting Correct

by using that method they protect themselves......... - correct uses

E) to protect Incorrect

to uses as modifier is wrong
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to us not used as modifier - flocks use blah blah to protect themselves

AndrewN could you please explain why A is wrong here ?

Hello, Taulark1. I will insert the original sentence below for reference.


The problem with the underlined portion, the noun phrase, is that wavelike movement, however coordinated it may be, is not synonymous with a method. For the phrase to work, we would expect it to comment on a complete thought rather than hijack the sentence. Compare to the following:

Flocks of birds... use highly-coordinated wavelike movement to protect themselves against predators, a strategy that...

Notice that the noun phrase after the comma is commenting on the previous clause, not on movement alone. In the sentence at hand, if we mean to explain the role of the movement, then we should see a visual cue that we are shifting into adverbial territory:

Flocks of birds... movement as a method to protect themselves...

Here, though, we would have to remove the comma after movement, and that is non-negotiable in the original sentence. This understanding alone could help us get rid of (B) and (C).

Anyway, I hope that helps with (A). Remember, your goal is not to chase answers in SC, but to select the option that most clearly and concisely expresses the vital meaning. The original sentence is unclear because it apparently is referring to movement itself as a method.

Thank you for thinking to ask me about this one, and, as always, good luck with your studies.

- Andrew
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It is a poor imitation of official question in which linking verb is used. That makes official one more precise.

In this, I would prefer A

Dear Friends,

Here is a detailed explanation to this question-

Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended meaning of this sentence is that flocks of birds and schools of fish instinctively use highly-coordinated wavelike movement, and in doing so protect against predators that would much rather attack an individual member that strays from the group.

Concepts tested here: Meaning + Modifiers + Verb Forms

• In the “noun + comma + phrase” construction, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• The introduction of present participle (“verb+ing”- “protecting” in this case) after comma generally leads to a cause-effect relationship.
• The infinitive verb form ("to + base form of verb" – “to + protect” in this sentence) is the preferred construction for referring to the purpose or intent of an action.

A: Trap. This answer choice incorrectly modifies "wavelike movement" with "a method to protect", incorrectly implying that the wavelike movement is a method that the flocks of birds and schools of fish instinctively use to protect against certain predators; the intended meaning is that by taking the action of using the wavelike movement, flocks of birds and schools of fish protect themselves against certain predators; please remember, in a “noun + comma + phrase” construction, the phrase must correctly modify the noun.

B: This answer choice incorrectly modifies "wavelike movement" with "as a method protecting", incorrectly implying that the wavelike movement is a method that the flocks of birds and schools of fish instinctively use to protect against certain predators; the intended meaning is that by taking the action of using the wavelike movement, flocks of birds and schools of fish protect themselves against certain predators; please remember, in a “noun + comma + phrase” construction, the phrase must correctly modify the noun.

C: This answer choice incorrectly modifies "wavelike movement" with "as a protection of", illogically implying that the wavelike movement is a protection of the flocks of birds and schools of fish against certain predators; the intended meaning is that by taking the action of using the wavelike movement, flocks of birds and schools of fish protect themselves against certain predators; please remember, in a “noun + comma + phrase” construction, the phrase must correctly modify the noun.

D: Correct. This answer choice correctly modifies "wavelike movement" with "protecting themselves against predators...group"; the use of the "comma + present participle (“verb+ing”- “protecting” in this case)" conveys the intended meaning - that flocks of birds and schools of fish instinctively use highly-coordinated wavelike movement, and in doing so protect against certain predators; please remember, the introduction of the present participle (“verb+ing”- “protecting” in this case) after comma generally leads to a cause-effect relationship.

E: Trap. This answer choice alters the meaning of the sentence through the phrase “to protect”; the use of the infinitive verb form ("to + base form of the verb" – “to + protect” in this sentence) modifies the verb “use”, incorrectly implying that flocks of birds and schools of fish purposefully use highly-coordinated wavelike movement for the purpose of protecting themselves from certain predators; the intended meaning is that flocks of birds and schools of fish instinctively use highly-coordinated wavelike movement, and in doing so protect against certain predators; please remember, the infinitive verb form ("to + base form of verb" – “to + protect” in this sentence) is the preferred construction for referring to the purpose or intent of an action.

Hence, D is the best answer choice.

To understand the concept of "Comma + Present Participles for Cause-Effect Relationships" on GMAT, you may want to watch the following video (~3 minutes):



To understand the concept of "Phrase Comma Subject" and "Subject Comma Phrase" on GMAT, you may want to watch the following video (~1minute):



All the best!
Experts' Global Team
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Hello, avinashiitp. Any question from a third party should be treated as a learning opportunity rather than as a definitive sign of GMAT™-readiness. Some such questions are constructed well while others unravel at the seams. Your goal is not to point to a particular official question and say that just because that question is similar, the answer has to be the same in another case. Your goal is always to assess the five iterations of the sentence on their own merits, as though these were the only five options that ever existed. You are welcome to disagree with me and other Experts and prefer the original sentence, but that does not either prove the correctness of your views or cast doubt on the points broached by the Experts. I have said my piece about (A), and so has Experts' Global. There might be some valuable opportunities for learning and growth by reading these responses (as well as those from the community at large).

Good luck with your studies.

- Andrew
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AndrewN , thanks for that awesome reply !

just a quick follow up question, would really appreciate the help in understanding this more.. 😅
Why cant this part act as an absolute phrase ? (as in modifying the entire clause) -
'a method to protect themselves against predators..'

Hello again, Taulark1. I think I explained above why we cannot interpret this method phrase as a comment on the entire clause, but to put it succinctly, the original sentence does not present a complete thought, so there is no clause for an absolute phrase to modify. Flocks use movement is not a standalone sentence within the context of what the sentence means to express. The verb use, paired with the noun movement, represents an unfinished thought. Compare to the complete thought Flocks fly quickly. The type of verb used changes the way the sentence operates. In the original sentence, the method phrase is understood, grammatically, to comment on movement (again, for reasons I have outlined earlier).

I hope it makes sense now. When you read about a meaning-based approach to SC, this type of situation qualifies. In both of my dummy flocks "sentences" above, we get a noun followed by a verb, but one can stand on its own while the other cannot. Language sure is strange.

- Andrew
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