Neuroscientists, having amassed a wealth of knowledge over the past

Question

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.

Option A
Option B
Option C
Option D
Option E

(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)

Solution

Sentence Analysis

Let’s look at the sentence structure:

  • Neuroscientists, (Main subject)
    • having amassed a wealth of knowledge (“having + verbed” modifier, also called perfect participle, modifying the main subject)
      • over the past twenty years (prepositional phrase modifies “having amassed”)
      • about the brain and its development from birth to adulthood, (prepositional phrase modifying “knowledge”)
  • are now drawing solid conclusions (Main verb – “are drawing”)
    • about (prepositional phrase modifying “conclusions”)
      • how the human brain grows (Noun clause i.e. a clause acting as a noun — acting as the first object of the preposition “about”)
      • and how babies acquire language. (Noun clause i.e. a clause acting as a noun — acting as the second object of the preposition “about”)

“Having verb-ed” form always indicates an action completed before another action. (This structure is called perfect participle. Just as past perfect indicates an action completed before certain past event, perfect participle indicates an action completed before another action, which is usually depicted in the form of a verb in a clause)

The sentence means that first Neuroscientists amassed a wealth of knowledge over the past twenty years, and now they are drawing solid conclusions about two things.

As is, the sentence communicates a logical meaning and is grammatically correct.

Option Analysis

(A) Correct.

(B) Incorrect. There is no verb parallel to “are” before ‘and’. “having amassed” is a modifier, not a verb.

The modifier “over the past twenty years” modifies “amassed” (providing information about when this action was done) and is four words long. The modifier “about the brain and its development from birth to adulthood” modifies “knowledge” and is ten words long. It’s preferable for clarity that we first present a shorter modifier and then the longer modifier, especially since the shorter modifier modifies an entity appearing earlier.

(C) Incorrect. There is no verb parallel to “are drawing” before ‘and’. “amassing” is a modifier, not a verb.

(D) Incorrect. Per this option, “drawing” (in the non-underlined part) is a “comma + verb-ing” modifier modifying the preceding clause. Since “drawing solid conclusions” is a separate action done by the Neuroscientists and is not a natural outcome of the preceding clause, the use of verb-ing is incorrect. Here are three sentences that demonstrate what I have talked about:

  • Ram won the chess championship, pushing himself to the top rank. (This is correct. The verb-ing “pushing” indicates a natural consequence of the clause and not a separate deliberate action by Ram)
  • Ram won the chess championship, celebrating his win in style. (This is incorrect. The verb-ing “celebrating” doesn’t indicate a natural consequence of the clause but is a deliberate action performed by Ram)
  • Ram won the chess championship and celebrated his win in style. (Correct. The two separate actions are indicated by two separate verbs)

(E) Incorrect. Has the same error as in option D.

Now, if you are cribbing ( 😛 ) that GMAT expects you to know such finer distinctions as highlighted in option D, stop cribbing! Why? Because you could have rejected options D and E since they are essentially the same. There is no reason to reject option E if you select option D and vice-versa. And you know that you can’t have two correct options in a GMAT question. Right? So, that is the way you could have rejected options D and E and arrived at the right answer. In case of finer subtleties, GMAT does give you a lifeline by providing two more-or-less same options. I have seen this pattern in other questions too, including this one.

About Chiranjeev Singh

An Alumnus of IIM Ahmedabad and with a score of 780 (2017) and 770 (2013) on GMAT and 99.98%ile on CAT, Chiranjeev is one of the most qualified GMAT tutors in India. Chiranjeev has earlier served as Director of Curriculum at e-GMAT. Chiranjeev has been helping students ace GMAT since 2012. He follows a concept-based methodology to teaching GMAT and is very committed to student success. You may contact him for any private GMAT tutoring needs at +91 9971 0010 67 or CJ@GMATwithCJ.com. He conducts online sessions for students across the world.

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