Dear Friends,
Here is a detailed explanation to this question-
johnycute wrote:
On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow, as seen in the rings visible in the cross sections of their trunks.
(A) On Earth, among the surest indications of sunspot cycles are believed to be the rate that trees grow
(B) On Earth, among the surest indications of sunspot cycles are, it is believed, the rate of tree growth
(C) On Earth, the rate at which trees grow is believed to be among the surest indications of sunspot cycles
(D) Among the surest indications on Earth of sunspot cycles, believed to be the tree growth rate
(E) Among the surest indications on Earth of sunspot cycles is believed to be the rate at which trees grow
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 rate at which trees grow, as seen in the rings visible in the cross sections of their trunks is believed to be among the surest indications on Earth of sunspot cycles.
Concepts tested here: Subject-Verb Agreement + Meaning + Modifiers + Grammatical Construction + Idioms• In a “noun + comma + phrase” construction, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• If "rate" is used as a noun "rate + that + clause + at", "rate + of + noun", "noun + rate", and "rate + at which + clause" are the correct idiomatic constructions.
A: This answer choice incorrectly uses the plural verb "are believed" to refer to the singular noun "rate". Further, Option A incorrectly uses the unidiomatic construction "rate (noun) + that + clause"; remember, if "rate" is used as a noun "rate + that + clause + at", "rate + of + noun", "noun + rate", and "rate + at which + clause" are the correct idiomatic constructions.
B: This answer choice incorrectly uses the plural verb "are" to refer to the singular noun "rate".
C: This answer choice incorrectly modifies the noun "the surest indications of sunspot cycles" with "as seen in the rings visible in the cross sections of their trunks", illogically implying that
all of the surest indications of sunspot cycles are seen in the rings visible in the cross sections of tree trunks; the intended meaning is that
one of the surest indications of sunspot cycles -
the rate at which trees grow - is seen in the rings visible in the cross sections of tree trunks; remember, in a “noun + comma + phrase” construction, the phrase must correctly modify the noun.
D: This answer choice fails to form a complete sentence; as "believed" and "seen" are past participles acting as modifiers, there is no active verb to act upon the subject "the tree growth rate".
E: Correct. This answer choice acts upon the independent subject noun "the rate" with the active verb "is believed" to form a complete thought, producing a complete sentence. Further, Option E correctly refers to the singular noun "the rate" with the singular verb "is believed". Moreover, Option E correctly modifies the noun "the rate at which trees grow" with the phrase "as seen in the rings visible in the cross sections of their trunks", conveying the intended meaning - that
one of the surest indications of sunspot cycles -
the rate at which trees grow - is seen in the rings visible in the cross sections of tree trunks. Additionally, Option E correctly uses the idiomatic construction "rate + at which + clause".
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 (~1 minute):
All the best!
Experts' Global Team
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