source: gmatprep 2, q. 30.

The Kwakiutl recognized one social unit larger than the tribe-the confederacy, which was a cluster of loosely knit, informally related neighboring tribes who interacted with themselves more often than between other tribes.

A. tribes who interacted with themselves more often than between
B. tribes who interacted among each other more often than among
C. tribes who interacted with one another more often than with
D. tribes, interacting among each other more often than between
E. tribes, interacting among one another more often than with

OA: C


Since there are more than two tribes interacting, we can not use "between". I eliminated A,D.
It seems that in E, interacting refers to "the confederacy", although I am not sure. If it does, then the interaction can not be among one another.
Between B and C, I am clueless. I would appreciate any help, thanks.

I would go with C
B is wrong because tribes cannot interact 'among' other tribes.
Let me write down the whole B option. If I remove the italicised parts in the sentence, it will not make sense.
The Kwakiutl recognized one social unit larger than the tribe-the confederacy, which was a cluster of loosely knit, informally related neighboring tribes who interacted among each other more often than among other tribes.

If it had been 'more often that with other tribes' it would have been better.

I do have a query here though. What is the difference between 'among' and 'amongst' ? Is it just new style and old style or is there be a difference in usage ?

2 idiom errors in (b):
* "interact" MUST be paired with "with". "interact between" and "interact among" are unidiomatic.
* "among each other" is unidiomatic (as is "between each other"); you should write "among themselves" or "between themselves". but, again, this doesn't work with "interact" anyway, so the issue is moot here.

I received a PM asking me to respond, but looks like Ron beat me to it!

To the poster who asked about "among" vs. "amongst" - the difference is essentially American English vs. British English. You'll see American English (among) on this test, because it's a US-based test.

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One question,
Is there any difference between "each other" and "one another"?

I think, each other is used for 2 things or units.

if there are more than 2 units , then we use one another

Please correct me if i am wrong

this sounds as though it could be correct.

i can't guarantee this 100%, though, until i've seen an OFFICIAL problem to confirm the distinction.

So the OA is C? In E, interacting also correctly modify the last clause right, it is wrong because of "interacting among one another" is incorrect?

thanks

Who is relative pronoun

Is it ok to say Tribes who? '

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Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working.

(d) and (e) contain a COMMA + -ING modifier that is used incorrectly.

a COMMA + -ING modifier is an adverbial modifier that modifies the entire clause to which it's attached, and is attributed to the subject of that clause.
in this context, you only want to modify the preceding noun ("tribes"), so COMMA + -ING is inappropriate.

what is the right answer??

C

the correct answer is in the original post.

it's written in white-on-white, so you'll have to highlight it (after "OA:") to see it.

Pls help confirm if my understanding is correct:

"infomally related..." is a "Verb-ed" modifier modify 'knit'. (Comma+Verb-ed modify the noun or noun phrase immediately precede it).
A modifier can be omitted, hence, the subject of "Comma + Interacting" here should be the "the confederacy". The Comma+ -ING here gramatically cannot modify "knit", since it's the object of the preceding clause.

Thanks for your feedback in advance

this is mostly incorrect.

first, it seems that you've mistaken "knit" for a noun. it's not; it's an adjective.
if you don't know that from mastery of the language, you can figure it out from the fact that "knit" is preceded by "loosely" -- an adverb. you can't put an adverb in front of a noun, a fact that's sufficient to prove that "knit" is not a noun.

the "-ed" part is also not a following modifier; it's a past participle that (together with the preceding adverb "informally") serves as an adjective. with "informally related" correctly considered as an adjective, this part ("loosely knit, informally related neighboring tribes") has the same construction as "big, ugly mess", except with adverbs in front of "big" and "ugly".

you are correct, though, about the subject of what is (incorrectly) being modified by the COMMA -ING modifier: "confederacy". technically, the subject and verb of the modified clause are "which was...", but "which" refers back to "confederacy".

remember that when you SOLVE the problem, you should not bother to figure out what is modified by a modifier, once you've determined that the modifier doesn't modify what it should modify. since you've already established that the modifier is incorrect, it's a waste of time to clarify the issue any further.
when you REVIEW the problems, on the other hand, it's quite useful to investigate such issues in full.