Dear Friends,
Here is a detailed explanation to this question-
scorpio7 wrote:
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 Chile.
(A) Columbus was the Incan highway, which, over 2,500 miles long and extending
(B) Columbus was the Incan highway, over 2,500 miles in length, which had 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
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