Scientists are analyzing the movement patterns of slime mold, which

Question

Scientists are analyzing the movement patterns of slime mold, which  grows outward to search for its food sources by retracting  from everything but the most efficient route, in an effort to better understand how to optimize traffic patterns.
 
(A) grows outward to search for its food sources by retracting
 
(B) grows outward to search for its food sources, and the slime mold retracts
 
(C) grows outward, searching for its food sources and retracting
 
(D) searches for its food sources by growing outward and retracts
 
(E) searches for its food sources and grows outward, retracting

MikeScarn · Accepted Answer

Hi  neha283   santorasantu  , this is a tough one. I'll try to attack this question from a couple angles. Hopefully one of them will suffice.

Meaning: 
Let's read the sentence without the modifier that is surrounded by comma's.

"Scientists are analyzing the movement patterns of slime mold in an effort to better understand how to optimize traffic patterns."

Okay, so scientists are trying to improve their understanding of how to optimize traffic patterns. Cool.  How do they plan on bettering their understanding?  They're going to look at slime mold.

Why look at slime mold?  Well, slime mold finds food by growing outwards. Once the mold finds some food, it then retracts from everything except the most efficient route to the food.

Let's check out some answer choices.

The mold grows outward  by retracting ? That's impossible. Is it growing outward or retracting?  Meaning error.

This once is icky. We added another comma here, so we can't remove the whole modifier to have that nice and clean sentence that I wrote at the beginning of this post.

"which grows outward" is clearly modifying "slime mold." Cool. I'm good with that.

What is "searching for its food sources and retracting from everything but the most efficient route" modifying? Is it modifying "slime mold"? It is modifying "Scientists?"

Further, The slime mold grows outward  and then  retracts, but growing outward does not  cause it to retract.

This one doesn't  sound  good to me either, but who cares? GMAC sure doesn't. It doesn't  sound  good because of the verb forms "searches for X by growing outward and retracts from Y." If we remove that Prepositional phrase: "for its food sources by growing outward," then it will sound a lot better.

We're looking great from a parallelism point of view. " searches  for X and  retracts  from Y"

This works great from a meaning perspective because it shows that the slime mold searches by growing outward  and  retracts from everything except the best route. These are two independent actions. They do not grow outward and retract at the same time.

I hope this helps someone.

neha283 · Answer

Hi, 
Can anyone tell why option D is correct and not C?

Option D says that it does 2 things (2 verbs joined with and) - searches and retracts. 
From what i understand from the question - it searched by 
1. growing outwards while 
2. retracting from everything but the most efficient route

Please correct me if my understanding is wrong.

Thanks!

Mankodim · Answer

According to me, the problem with option C is that it breaks the continuity of Scientists are analyzing the movement patterns of slime mold,...,in an effort to better understand how to optimize traffic patterns

santorasantu · Answer

Gmatninja can you please help with this sentence.

RastogiSarthak99 · Answer

Slime mold -- retracts from everything

this should help you eliminate choices A, C, and E.

Then, choice B is just redundant in its use of slime mold again. Hence, choice D.

reneew1024 · Answer

On a separate note, kinda confused by the "but", can anyone explain the use of "but" here?

EducationAisle · Answer

but  is used to depict  except  here.

AjiteshArun · Answer

To add to  EducationAisle  's reply, this  but  is actually a preposition and not a conjunction. We can also use  apart from  in addition to  except  to see what this  but  means. For example:

The dictator's demands were anything but simple.  ← This is another way of saying that the demands were  not  simple ("they were anything except/apart from simple").

NoMatterWhat · Answer

please explain how to eliminate options and isn't there any pronoun error in D; shouldn't "which " follow 'and'.

Bombsante · Answer

Scientists are analyzing the movement patterns of slime mold, which  grows outward to search for its food sources by retracting  from everything but the most efficient route, in an effort to better understand how to optimize traffic patterns.

Damn, It took me 3 minutes to crack the correct answer! The sentence is trying to say that Scientists are analyzing the movement patterns of slime mold to better understand how to optimize traffic patterns. The sentence between the commas must contain information which presents the reason why Scientists are studying slime molds only. Read all options without prepositional phrases to simplify the sentence. Probably this is also one way of eliminating wrong answers

(A) grows outward to search for its food sources by retracting  (grows outward by retracting?? Illogical meaning, incorrect)

(B) grows outward to search for its food sources, and the slime mold retracts  (grows outward and the slime mold retracts, inconsistent parallelism. Incorrect)

(C) grows outward, searching for its food sources and retracting  (grows outward and retracting? incorrect use of tenses)

(D) searches for its food sources by growing outward and retracts  (searches and retracts, correct parallel structure, best of all)

(E) searches for its food sources and grows outward, retracting  (searches , retracting. Doesn't make any sense. Incorrect)

I am not sure how to eliminate answer choice B if it read "grows outward to search for its food sources and retracts"

I am keen to read some thoughts on this.

akadiyan · Answer

Scientists are analyzing the movement patterns of slime mold, which grows outward to search for its food sources by retracting from everything but the most efficient route, in an effort to better understand how to optimize traffic patterns.

Damn, It took me 3 minutes to crack the correct answer! The sentence is trying to say that Scientists are analyzing the movement patterns of slime mold to better understand how to optimize traffic patterns. The sentence between the commas must contain information which presents the reason why Scientists are studying slime molds only. Read all options without prepositional phrases to simplify the sentence. Probably this is also one way of eliminating wrong answers

(A) grows outward to search for its food sources by retracting (grows outward by retracting?? Illogical meaning, incorrect)

(B) grows outward to search for its food sources, and the slime mold retracts (grows outward and the slime mold retracts, inconsistent parallelism. Incorrect)

(C) grows outward, searching for its food sources and retracting (grows outward and retracting? incorrect use of tenses)

(D) searches for its food sources by growing outward and retracts (searches and retracts, correct parallel structure, best of all)

(E) searches for its food sources and grows outward, retracting (searches , retracting. Doesn't make any sense. Incorrect)

I am not sure how to eliminate answer choice B if it read "grows outward to search for its food sources and retracts"

I am keen to read some thoughts on this.

. Eliminate option A, B and C. We are left with options D and E. Now we can revisit the underlined part once more to understand the meaning of it. The meaning here is Slime mold searches food resources by growing outward and then retracts. Option E says search for food and grow outward like they are 2 different activity. We can eliminate option E. Our answer is option D which clearly conveys the meaning that slime mold searches for food by growing outward and retracting Ans: D

SALAKSHYA · Answer

Hi Mike,
Thanks for explanations. 
I have doubts on double modifier, can a modifier can modify another modifier?
for example in this case in option C,  grows outward, searching for its food sources and retracting 
can  searching for its food sources and retracting  modify  which grows outward ?

Saasingh · Answer

Hello mikemcgarry AjiteshArun GMATNinja GMATNinjaTwo generis

Hope you are all doing well. I would request some assistance on this problem.

Could you please correct my reasoning on option A ?

Scientists are analyzing the movement patterns of slime mold, which grows outward to search for its food sources by retracting from everything but the most efficient route, in an effort to better understand how to optimize traffic patterns.

I understand how option D is correct. But I understood option A as follows :

Scientists are analyzing the movement patterns of slime mold, which grows outward to search (BY RETRACTING) for its food sources BY RETRACTING from everything but the most efficient route, in an effort to better understand how to optimize traffic patterns.

According to OE and other people, I see that people say "BY RETRACTING" is modifying "GROWS OUTWARD". As in, how can the slime mold grow outward BY RETRACTING. I get it.

But I implied the meaning as : Grows outward TO SEARCH for food BY RETRACTING (modifying the "to search").

So for me, option A means : the slime mold grows outward to search for food sources, search by retracting from all routes except the most efficient route.
The meaning as above seems to be logical, I guess. Does it have anything to do with prepositions? I see that "Grows" is the verb and "to search" is a preposition. I can't see how can we be certain that "retracting" is modifying the "Grows" verb.

Or is it because of the intention (to search) in option A ? How can slime mold GROW TO SEARCH. (this makes some sense to me in order to eliminate this option).

Maybe I am missing something. Could you please enlighten ?

Thankyou in advance for your help

Regards,
Saakhi

Regards, Saakhi

AjiteshArun · Answer

Hi  Saasingh ,

Did you mean to say that "D is correct"? That's the OA.

I agree that there is a meaning issue in A, because the  ~ retraction should happen after the  ~ growing outward. Firstly, if we say that slime mold grows outward by retracting from everything except the most efficient route, that's more like...  contracting , because in order to "retract", it should have already occupied the space that it plans to retract from. Secondly, think about how slime mold would find the most efficient way to its food. It probably can't. It probably (a) grows until it finds food and then (b) focuses on just those areas, removing itself from any (other) areas that don't have food.

Of these two, I'd prefer the first approach, as the second one needs us to bring in slightly more outside information than I'm comfortable with. However, as this question has been tagged as a Manhattan question, I'm tagging  DmitryFarber  for you as well.

Saasingh · Answer

Hi AjiteshArun Thanks for your quick response. Yes I meant option D is the OE. I think I understand a little. I was understaning A as : TO SEARCH by Retracting .. so it felt reasonable. Because for everyone, A is eliminated because of "grow outward by retracting" logic, and I understand that as well. But I was attaching the " by retracting" to the "to search", just like it is presently in option D. So I was really confused with option A. But yes, now looking back at A makes some sense. Grow...to search...by retract --> but retract is the opposite of growing (which I didn't apply). Yes, we cant grow outward to search by going backward !! Your second reasoning makes total sense to me. Thank you !

Regards, Saakhi Posted from my mobile device

Alpha420 · Answer

A. Meaning error. "By retracting from everything but most efficient route.." is not clear what it is modifying?
Does it grow outward by retracting from all routes but ME or does it search for food by retracting. --  Incorrect

B. No need to mention "slime mold" again with retracts since its a parallel list. --  Incorrect 
Note : grows outward to search for its food sources, and retracts would also have been incorrect since COMMA + AND is used to join 2 independent clauses.

C. Searching and retracting are not parallel. Retract and search are 2 independent actions. 
Also what does this verb-ing modifier seems to modify? Noun in preceding clause - Scientists/slime mold. Its logically not correct. --  Incorrect

D. maintains parallelism - searches and retracts. "its" has proper logical antecedent - slime mold. Parallel items "searches" and "retracts" are properly connected by conjunction "and". --  Correct

E. Slime mold searches by growing outwards. These are not independent actions. "retracting..." is again verb-ing modifier, its not clear the entity it is modifying. --  Incorrect

So answer is D.

Jarvis07 · Answer

Hello experts  GMATGuruNY ,  AjiteshArun ,  generis , @MentorTutoring, @EducationAisle;

Could anyone please help me with this doubt:

According to  MikeScarn :

If we remove the modifier " which grows outward ", it clearly refers to " slime mold ". Also, " its " is singular and has to point to " slime mold ". Is this correct to say that the referent of " searching " is ambiguous?

Scientists are analyzing the movement patterns of slime mold, which

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Scientists are analyzing the movement patterns of slime mold, which

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