Dear Friends,
Here is a detailed explanation to this question-
betterscore wrote:
Digging in sediments in northern China, evidence has been gathered by scientists suggesting that complex life-forms emerged much earlier than they had previously thought.
(A) evidence has been gathered by scientists suggesting that complex life-forms emerged much earlier than they had
(B) evidence gathered by scientists suggests a much earlier emergence of complex life-forms than had been
(C) scientists have gathered evidence suggesting that complex life-forms emerged much earlier than
(D) scientists have gathered evidence that suggests a much earlier emergence of complex life-forms than that which was
(E) scientists have gathered evidence which suggests a much earlier emergence of complex life-forms than that
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 scientists were digging in sediments in northern China, and they have gathered evidence suggesting that complex life-forms emerged much earlier than previously thought.
Concepts tested here: Meaning + Modifiers + Idioms + Pronouns Awkwardness/Redundancy• In a “phrase + comma + noun” construction, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• When the chronology is clear because of terms such as "before/after/when/earlier/later"…or because of clear mention of dates, use past perfect tense is not required, though not incorrect either.
• “that” is used to provide information needed to preserve the core meaning of the sentence, and the “comma + which” construction is used to provide extra information.
A: This answer choice incorrectly uses "Digging in sediments in northern China" to modify "evidence", illogically implying that
the evidence was digging in sediments in northern China; the intended meaning is that
scientists were digging in sediments in northern China; please remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun. Further, Option A redundantly uses the past perfect tense verb "had...thought" in conjunction with the adverb "previously"; please remember, when the chronology is clear because of terms such as "before/after/when/earlier/later"…or because of clear mention of dates, use past perfect tense is not required, though not incorrect either. Additionally, option A uses the passive voice construction "evidence has been gathered", leading to awkwardness and redundancy.
B: This answer choice incorrectly uses "Digging in sediments in northern China" to modify "evidence", illogically implying that
the evidence was digging in sediments in northern China; the intended meaning is that
scientists were digging in sediments in northern China; please remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun. Further, Option B redundantly uses the past perfect tense verb "had...thought" in conjunction with the adverb "previously"; please remember, when the chronology is clear because of terms such as "before/after/when/earlier/later"…or because of clear mention of dates, use past perfect tense is not required, though not incorrect either.
C: Correct. This answer choice correctly uses "Digging in sediments in northern China" to modify "scientists", conveying the intended meaning - that
scientists were digging in sediments in northern China. Further, Option C avoids the pronoun error seen in Options D and E, as it uses no pronouns. Additionally, Option C avoids the idiom error seen in Option E, as it correctly uses "that" to refer to information that is vital to the core meaning of the sentence - the fact that the evidence suggests that complex life-forms emerged much earlier than previously thought. Besides, Option C is free of any awkwardness or redundancy.
D: This answer choice suffers from a pronoun error, as the pronoun "that" lacks a clear referent. Further, Option D uses the needlessly wordy phrase "earlier emergence of complex life-forms than that which was", leading to awkwardness and redundancy.
E: This answer choice suffers from a pronoun error, as the pronoun "that" lacks a clear referent. Further, Option E incorrectly uses "which" to refer to information that is vital to the core meaning of the sentence - the fact that the evidence suggests that complex life-forms emerged much earlier than previously thought; please remember, “that” is used to refer to information needed to preserve the core meaning of the sentence, and the “comma + which” construction is used to provide extra information. Additionally, Option E is needlessly wordy due to the use of "that", as "that" can be removed without a loss of clarity.
Hence, C 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):
To understand the concept of "Which" vs "That" on GMAT, you may want to watch the following video (~2 minutes):
All the best!
Experts' Global Team