The greatest road system built in the Americas prior to the arrival of

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 the Incan highway was the greatest road system built in the Americas prior to the arrival of Christopher Columbus, and it was over 2,500 miles long because it extended from northern Ecuador through Peru to southern Chile.

Concepts tested here: Meaning + Tenses + Grammatical Construction

• The past perfect tense (marked by the use of helping verb "had") is only used when a sentence contains two actions in the past, which took place at different times; the helping verb "had" is used with the action in the "greater past".
• The introduction of the present participle ("verb+ing"- “extending” in this case) after comma generally leads to a cause-effect relationship.
• Information that is vital to the core meaning of the sentence cannot be placed between commas.

A: This answer choice fails to form a complete sentence; as "extending" is a present participle ("verb+ing") acting as a noun modifier, there is no active verb to act upon the pronoun "which", the subject of the second clause of the sentence.

B: This answer choice incorrectly uses the past perfect tense verb "had extended" to refer to one of two actions that took place simultaneously in the past - the Incan highway being the greatest road system built in the Americas prior to the arrival of Christopher Columbus and the highway extending from northern Ecuador through Peru to southern Chile; please remember, the past perfect tense (marked by the use of helping verb "had") is only used when a sentence contains two actions in the past, which took place at different times; the helping verb "had" is used with the action in the "greater past". Further, Option B incorrectly places information vital to the core meaning of the sentence - the fact that the Incan highway was over 2,500 miles in length - between two commas; please remember, information vital to the core meaning of the sentence cannot be placed between commas.

C: This answer choice fails to form a complete sentence; as "was" and "extended" are both parts of a modifying phrase, there is no active verb to act upon the noun "the Incan highway".

D: This answer choice alters the meaning of the sentence through the phrase "being over 2,500 miles in length, was extended"; the construction of this phrase reverses cause and effect, incorrectly implying that because the Incan highway was over 2,500 miles in length, someone extended it from northern Ecuador through Peru to southern Chile; the intended meaning is that the Incan highway was over 2,500 miles long because it extended from northern Ecuador through Peru to southern Chile.

E: Correct. This answer choice acts upon the subject noun "the Incan highway" with the active verb "was" to form a complete thought, leading to a complete sentence. Further, Option E uses the phrase "extending from northern Ecuador through Peru to southern Chile"; the use of the "comma + present participle (verb+ing" - "extending" in this sentence) correctly conveys the intended meaning - that the Incan highway was over 2,500 miles long because it extended from northern Ecuador through Peru to southern Chile; remember, the introduction of the present participle ("verb+ing"- “extending” in this case) after comma generally leads to a cause-effect relationship. Additionally, Option E avoids the tense error seen in Option B, as it uses the present participle ("verb+ing" - "extending" in this sentence) rather than an active verb, such as "had extended" in Option B. Besides, Option B avoids the grammatical construction error seen in Option B, as it places no information between commas.

Hence, E is the best answer choice.

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



To understand the concept of "Extra Information Between Commas" on GMAT, you may want to watch the following video (~1 minute):



To understand the concept of "Past Perfect Tense" on GMAT, you may want to watch the following video (~2 minutes):



All the best!
Experts' Global Team

The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chili.

A. Underlined portion
B. Columbus was the Incan highway, over 2,500 miles in length, and extended
C. Columbus, the Incan highway, which was over 2,500 miles in length and extended
D. Columbus, the Incan highway, being over 2,500 miles in length, was extended
E. Columbus, the Incan Highway was over 2,500 miles long, extending


Ans shud be E.
Reason: 'extending ......' is a participle-modifier. In case of 'C' the sentence is not complete. The Incan highway should be described further in case of 'C'.
Let me know the OA.

Can someone explain the difference between C and E. They are the clear contenders in this question


The greatest road system built in the Americas ( modifies) .... the Incan highway
IMO E.

The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chili.


C. Columbus, the Incan highway, which was over 2,500 miles in length and extended==> THIS OPTION DONT HAVE A VERB FOR THE SUBJECT..INCAN HIGH
HIGHLITED PART IS ACTING AS A MODIFIER...HENCE THIS ONE IS A FRAGMENT.

E. Columbus, the Incan Highway was over 2,500 miles long, extending==>THIS ONE HAS CLEARLY HAVE A SUB-VERB PAIR.
MOREOVER EXTENDING IS MODIFYING THE INCAN HIGHWAY..

HOPE IT HELPS

In A, the which-clause (which...Chile) lacks a verb.
Eliminate A.

In C, the Incan highway (subject) lacks a verb.
Eliminate C.

With regard to B and D: extended and extending convey different meanings.
Case 1: a highway extended implies that SOMEONE STRETCHED the highway beyond its initial length.
Case 2: a highway extending implies that the HIGHWAY ITSELF was long enough to STRETCH across the indicated distance.
The intended meaning here is Case 2.
Eliminate B and D.

The correct answer is E.

Analysis of the OA:
The greatest road system built in the Americas prior to the arrival of Christopher Columbus, the Incan highway was over 2,500 miles long, extending from northern Ecuador through Peru to Southern Chile.
Here, the subject of the sentence is the Incan highway.
The greatest road system is as an APPOSITIVE serving to DEFINE the Incan highway.
The COMMA + VERBing modifier (extending from Northern Ecuador through Peru) serves an as adverb modifying the preceding clause, providing context for HOW the Incan highway WAS over 2,500 miles long.

The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chili.

- Lets analyze the question- subject are highlighted in Bold and verb in italic font

Clause 1 : The greatest road system built in the Americas prior to the arrival of Christopher Columbus wasthe Incan highway
Clause 2: which, over 2,500 miles long and
extending from northern Ecuador through Peru to southern Chili.

So 2nd clause do not have any verb.

A. Underlined portion
B. Columbus was the Incan highway, over 2,500 miles in length, and extended - "Comma + and" starts a new clause, which do not have any subject.

C. Columbus, the Incan highway, which was over 2,500 miles in length and extended - Clause 1 do not contain the verb and extended is a modifier, which is not parallel to was over

D. Columbus, the Incan highway, being over 2,500 miles in length, was extended - Shift the main focus of scentence and use of being is incorrect here.

E. Columbus, the Incan Highway was over 2,500 miles long, extending - extending is modifying the Greatest road system and correctly expressing intent of the sentence. This is correct answer

Structurally B is completely wrong. "The Incan Highway" should be placed between two commas as it has been appropriately done in E. Moreover, "long" and "extend" do not belong to the same list of items. Hence, "and" is not needed here at all.

The incan highway is modifying Columbus in CDE. So out
between A and B
A is wrong because of wrong usage of extending....it is not a continuous process..

Here "extending" is not a verb, but a participle. Therefore "extending" does not necessarily mean a continuous process. Option A is wrong because the relative clause starting with "which" does not have a verb.

Please, note that the phenomenon of extension from Ecuador through Chile is a modifier that describes the enormous length of the road. In B, the second part is a fragment because it does not have a subject. Even so, because the extension through three countries is a describer or modifier of the system running for 2500 miles long, the second part should have been placed with just a comma rather than with a conjunction.
All in all, the important point is that B is incorrect and time to rollover to the remaining choices.

B without'and'

Without the conjunction 'and', the sentence will be a double verbed clause with the Incan highway as the subject and two verbs namely ' was'and 'extended' without a proper connector. Obviously, this is wrong, some kind of a fragment, without a subject for the second part.
It is also not clear whether somebody extended the highway after some time or whether the highway ran the whole distance from day one without additional laying.
The most obvious and easily visible error seems to the parallelism error with a clause on one side of the conjunction and just a predicate on the other
I didn't go further on B because that much was enough for me to understand that wasn't among the contenders.

The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chili.

A. Columbus was the Incan highway, which, over 2,500 miles long and extending
- "and extending" = incorrect. ", which" not necessary b/c you're not giving it a verb.

B. Columbus was the Incan highway, over 2,500 miles in length, and extended
- "and extended" = incorrect. "over 2,500 miles in length" = incomplete - where is verb? also, "in length" should be "long"

C. Columbus, the Incan highway, which was over 2,500 miles in length and extended
- "in length" should be "long". This is awkward, wordy construction. "and extended" = incorrect.

D. Columbus, the Incan highway, being over 2,500 miles in length, was extended
- "being" = incorrect. also, "was extended" = incorrect. the road system was not extended. "in length" should be "long". This is awkward, wordy construction.

E. Columbus, the Incan Highway was over 2,500 miles long, extending
- correct as is

key thing to note here is the STRUCTURE of the sentence: OPENING MODIFIER --> MAIN POINT --> MODIFIER
> if you can spot this, notice the last phrase is a modifier, so it's logical to begin that with "verb-ing" and not "AND + SOMETHING".

Kudos please if you find helpful

here when we look at the statement we see that the first half of the sentence is talking about the greatest road system which is in present tense ..
so the other part must not be in the past tense .. extended is wrong and also the use of the word was is not correct.
In a the verb was is not correctly used .
So the answer is E.

though there are many ways to look at this problem but probably the shortest way to do this problem correct is this way

This question tests Parallelism and Modifiers, always remember whenever you see a Parallelism indicator like 'And', you should always first look for the parallelism error, that being said:

Hello daagh,
In option B I thought 'was' and 'extended' were parallel! Both in past tense. When u say in B one is a phrase n the other a clause can u demarcate them for me please?

Hi daagh generis

Is (B) wrong or is it just that (E) is preferable over (B) ?

The Incan highway extended before Christopher Columbus is implied in (B) which does convey the intended/correct meaning, doesn't it ? Or the timeline (before/after) is additional information not available in the original (incorrect) sentence.

Dear experts,
RonPurewal egmat GMATNinja GMATNinjatwo @empowergmat daagh mikemcgarry
I have the same doubt.
"Verb-ing + comma" plays 2 major roles - either it presents the result of previous clause or it presents the how aspect of the previous clause. However, in addition to this, the doer of the action needs to be the same.
While, I am thoroughly convinced that "extending ..." clearly describes the "Incan highway" I cannot convince myself about how can Incan highway be the doer of the action "extending .."