Dear Friends,
Here is a detailed explanation to this question-
jerrywu wrote:
Scientists claim that the discovery of the first authenticated mammal bones in amber could provide important clues of determining, in addition to how, when mammals colonized the islands of the West Indies.
(A) of determining, in addition to how, when mammals colonized the islands of the West Indies
(B) in the determination of how and when the islands of the West Indies were colonized by mammals
(C) to determine how mammals colonized the islands of the West Indies and when they did
(D) for determining when the islands of the West Indies were colonized by mammals and how they were
(E) for determining how and when mammals colonized the islands of the West Indies
Meaning is crucial to solving this problem:Understanding the intended meaning is key to solving this question; the intended meaning is that the discovery of the first authenticated mammal bones in amber could provide important clues for determining when the islands of the West Indies were colonized by mammals and how the islands were colonized by mammals.
Concepts tested here: Meaning + Pronouns + Verb Forms + Grammatical Construction + Awkwardness/Redundancy• Information important to the core meaning of the sentence should not be placed between two commas.
• "did so" is used to refer to verbs.
• The infinitive verb form ("to + base form of verb" - "to + determine" in this case) is the preferred construction for referring to the purpose or intent behind an action.
A: This answer choice alters the meaning of the sentence through the phrase "clues of determining"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that the discovery of the first authenticated mammal bones in amber could provide important clues for determining when the islands of the West Indies were colonized by mammals and how the islands were colonized by mammals. Further, Option A incorrectly places information important to the core meaning of the sentence - the fact that the discovery could also provide important clues for determining
how mammals colonized the islands of the West Indies - between two commas; remember, information important to the core meaning of the sentence should not be placed between two commas.
B: This answer choice uses the needlessly wordy phrase "in the determination of", leading to awkwardness and redundancy.
C: This answer choice incorrectly uses "did" to refer to the action "colonized the islands of the West Indies"; this usage leads to an incomplete sentence, as in this case, "did" is merely a helping verb, not an active verb; remember, "did so" is used to refer to verbs. Further, Option C alters the meaning of the sentence through the phrase "to determine"; the use of the infinitive verb form ("to + base form of verb" - "to + determine" in this case) incorrectly implies that the discovery could provide clues
for the purpose of determining when the islands of the West Indies were colonized by mammals and how the islands were colonized by mammals; the intended meaning is that the discovery could provide clues
that could determine when the islands of the West Indies were colonized by mammals and how the islands were colonized by mammals; remember, the infinitive verb form ("to + base form of verb" - "to + determine" in this case) is the preferred construction for referring to the purpose or intent behind an action. Additionally, Option C suffers from pronoun ambiguity, as it is unclear whether "they" refers to "mammals" or "scientists".
D: This answer choice fails to form a complete sentence; here "were" does not form a complete simple past tense verb phrase, rather it is simply part of a simple past tense verb phrase in the passive voice. Further, Option D suffers from pronoun ambiguity, as it is unclear whether "they" refers to "mammals" or "scientists".
E: Correct. This answer choice avoids the verb form error seen in Options D and E, as it acts upon the noun "mammals" with the active verb "colonized" to form a complete thought, leading to a complete sentence. This answer choice uses the phrase "for determining", conveying the intended meaning - that the discovery could provide clues
that could determine when the islands of the West Indies were colonized by mammals and how the islands were colonized by mammals. Additionally, Option E avoids the pronoun ambiguity seen in Options C and D, as it uses no pronouns. Option E also avoids the grammatical construction error seen in Option A, as it places no information between commas. Besides, Option E is free of any awkwardness or redundancy.
Hence, E is the best answer choice.To understand the usage of a pair of commas on GMAT, you may want to watch the following video (~4 minutes):
All the best!
Experts' Global Team
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Updated on: 29 Apr 2020, 05:07
25%
(medium)
77%
(01:17)
correct 
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