Dear Friends,
Here is a detailed explanation to this question-
RenukaD wrote:
Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.
(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the human brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
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 neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood.
Concepts tested here: Meaning + Grammatical Construction• The introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.
A: Correct. This answer choice acts upon the subject - "Neuroscientists" - with the independent verb "are now drawing" to form a complete thought, leading to a complete sentence. Further, Option A uses the phrases "having amassed a wealth of knowledge over the past twenty years" and "are now drawing", conveying the intended meaning - that
over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain
undergoes from birth to adulthood, and
as a separate action, they are now drawing solid conclusions about how the human brain grows and how babies acquire language.
B: This answer choice fails to form a complete sentence; "having amassed" is part of a modifying phrase, and "are now drawing" is part of a dependent clause, meaning there is no independent verb to act upon the subject - "Neuroscientists". Further, Option B alters the meaning of the sentence through the phrase "development from birth to adulthood over the past twenty years"; the construction of this phrase incorrectly implies that over an
unspecified amount of time neuroscientists have amassed a wealth of knowledge about the development the human brain
underwent over the past twenty years,
specifically, from birth to adulthood; the intended meaning is that
over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain
undergoes from birth to adulthood.
C: This answer choice fails to form a complete sentence; "amassing" is a present participle acting as a noun modifier, and "are now drawing" is part of a dependent clause, meaning there is no independent verb to act upon the subject - "Neuroscientists". Further, Option C alters the meaning of the sentence through the phrase "development from birth to adulthood over the past twenty years"; the construction of this phrase incorrectly implies that over an
unspecified amount of time neuroscientists have amassed a wealth of knowledge about the development the human brain
underwent over the past twenty years,
specifically, from birth to adulthood; the intended meaning is that
over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain
undergoes from birth to adulthood.
D: The sentence formed by this answer choice alters the meaning of the sentence through the phrase "now drawing solid conclusions"; the use of the "comma + present participle ("verb+ing" - "drawing" in this sentence)" construction incorrectly implies that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the human brain and its development from birth to adulthood, and
as a result, they are now drawing solid conclusions about how the human brain grows and how babies acquire language; the intended meaning is that neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and,
as a separate action, over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood; remember, the introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.
E: The sentence formed by this answer choice alters the meaning of the sentence through the phrase "now drawing solid conclusions"; the use of the "comma + present participle ("verb+ing" - "drawing" in this sentence)" construction incorrectly implies that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the human brain and its development from birth to adulthood, and
as a result, they are now drawing solid conclusions about how the human brain grows and how babies acquire language; the intended meaning is that neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and,
as a separate action, over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood; remember, the introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.
Hence, A 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):
All the best!
Experts' Global Team
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