Dear Friends,
Here is a detailed explanation to this question-
pqhai wrote:
Unlike frogs that metamorphose from tadpoles into adults within a one-year period, it takes three to four years for the mountain yellow-legged frog of the Sierra Nevada to reach adulthood, and so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter.
(A) it takes three to four years for the mountain yellow-legged frog of the Sierra Nevada to reach adulthood, and so they are
(B) it takes the mountain yellow-legged frog of the Sierra Nevada three to four years until it reaches adulthood, and therefore it is
(C) in the Sierra Nevada, mountain yellow-legged tree frogs take three to four years to reach adulthood, thus being
(D) mountain yellow-legged frogs of the Sierra Nevada take three to four years until they reach adulthood, thus
(E) mountain yellow-legged frogs of the Sierra Nevada take three to four years to reach adulthood, and so they are
Meaning is crucial to solving this problem:Understanding the intended meaning is key to solving this question; the intended core meaning of this sentence is that the mountain yellow-legged frogs of the Sierra Nevada reach adulthood in three to four years, so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter.
Concepts tested here: Meaning + Modifiers + Comparison + Pronouns• In the “phrase + comma + noun” and “noun + comma + phrase” constructions, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• A pronoun can only have one referent in a sentence.
• A comparison must always be made between similar elements.
A: This answer choice incorrectly compares "frogs that metamorphose from tadpoles into adults within a one-year period" to the placeholder pronoun "it"; remember, a comparison can only be made between similar things.
B: This answer choice incorrectly compares "frogs that metamorphose from tadpoles into adults within a one-year period" to the placeholder pronoun "it"; remember, a comparison can only be made between similar things. Further, Option B incorrectly uses "it" both as a placeholder pronoun and to refer to the noun phrase "the mountain yellow-legged frog of the Sierra Nevada"; remember, a pronoun can only have one referent in a sentence. Additionally, Option B alters the meaning of the sentence through the phrase "takes...three to four years until it reaches adulthood"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that the mountain yellow-legged frogs of the Sierra Nevada reach adulthood in three to four years.
C: This answer choice incorrectly uses "in the Sierra Nevada" to modify "mountain yellow-legged tree frogs", incorrectly implying that mountain yellow-legged tree frogs reach adulthood in three to four years
if they are in the Sierra Nevada; the intended meaning is that the mountain yellow-legged tree frogs
native to the Sierra Nevada reach adulthood in three to four years; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun.
D: This answer choice alters the meaning of the sentence through the phrase "take three to four years until they reach adulthood"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that the mountain yellow-legged frogs of the Sierra Nevada reach adulthood in three to four years. Further, Option D incorrectly modifies "adulthood" with "thus restricted to deeper bodies of water...winter", illogically implying that
the adulthood of the frogs was restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter; the intended meaning is that
the frogs themselves are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter; remember, in a “noun + comma + phrase” construction, the phrase must correctly modify the noun.
E: Correct. This answer choice uses the phrase "take three to four years to reach adulthood" and avoids the modifier error seen in Option C, as it uses the phrase "mountain yellow-legged frogs of the Sierra Nevada", conveying the intended meaning - that the mountain yellow-legged tree frogs
native to the Sierra Nevada reach adulthood in three to four years. Moreover, Option E avoids the modifier error seen in Option D, as it uses the phrase "and so they are restricted to deeper bodies of water...winter", conveying the intended meaning - that "they" -
the frogs themselves - are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter. Further, Option E avoids the pronoun error seen in Option B, as it uses the pronoun "they" to refer to only one referent - "mountain yellow-legged frogs of the Sierra Nevada". Additionally, Option E correctly compares "frogs that metamorphose from tadpoles into adults within a one-year period" with "mountain yellow-legged frogs of the Sierra Nevada".
Hence, E is the best answer choice.To understand the concept of "Phrase Comma Subject" and "Subject Comma Phrase" on GMAT, you may want to watch the following video (~1minute):
All the best!
Experts' Global Team
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17 Apr 2013, 10:26
19%
(01:10)
wrong 
