thanhmaitran wrote:
Researchers studying
the brain scans of volunteers who pondered ethical dilemmas have found that the basis for making tough moral judgments is emotion, not logic or analytical reasoning.
(A) the brain scans of volunteers who pondered ethical dilemmas have found that the basis for making tough moral judgments is
(B) the brain scans of volunteers who pondered ethical dilemmas and found the basis to make tough moral decisions to be
(C) the brain scans of volunteers pondering ethical dilemmas and found that the basis for making tough moral decisions is
(D) volunteers’ brain scans while pondering ethical dilemmas have found the basis to make tough moral judgments to be
(E) volunteers’ brain scans while they pondered ethical dilemmas have found that the basis for making tough moral judgments is
Brain Scans (A) CORRECT
(B) Structure (studying…and found); Idiom (the basis to make)
(C) Structure (studying…and found)
(D) Idiom (the basis to make); Modifier / Meaning (while pondering)
(E) Pronoun (while they pondered)
First glanceNearly the entire sentence is underlined, so keep an eye out for the Big Four: Structure, Meaning, Modifiers, and Parallelism.
Issues(1) Structure: studying…and foundAnswers (B) and (C) both insert the word and before found, changing the sentence structure. (A), (D), and (E) use the helper verb have before found instead. Which sentence structure is correct?
Researchers studying…
(A) ...the brain scans...have found that the basis...is emotion
(B) …the brain scans…and found the basis…to be emotion
(C) …the brain scans…and found that the basis…is emotion
(D) ...the brain scans...have found the basis...to be emotion
(E) ...the brain scans...have found that the basis...is emotion
Studying the brain scans modifies researchers. In one interpretation of (B) and (C), the core subject and verb are researchers and found. In this case, there should not be an and between the subject and verb (researchers found). Alternatively, the word found could be seen as parallel to pondered: volunteers who pondered…and found. In this case, there is no main verb connected with the subject researchers at all, since all of the verbs are contained within modifiers. Under either interpretation, neither (B) nor (C) is a complete sentence; eliminate both. In (A), (D), and (E), the core subject and verb are researchers have found; this is correct.
(2) Idiom: the basis to makeThe answer choices flip back and forth between the basis for making and the basis to make.
The correct idiom is the basis for: the basis for doing X is Y. Eliminate answers (B) and (D).
(3) Topic: Modifier / Meaning: while ponderingPronoun: while they pondered
The opening structure of each choice changes.
(A) & (B) the brain scans of volunteers who pondered
(C) the brain scans of volunteers pondering
(D) volunteers’ brain scans while pondering
(E) volunteers’ brain scans while they pondered
While it is possible to construct a correct option starting with volunteers’ brain scans, in this case choices (D) and (E) are faulty. In (D), the sentence reads: Researchers studying X while pondering Y. This parallel structure indicates that the researchers were pondering ethical dilemmas, not the volunteers. While it is possible in general for researchers to ponder ethical dilemmas, that isn't what this sentence describes.
Answer (E) reads: Researchers studying volunteers’ brain scans while they pondered ethical dilemmas. In this case, the pronoun is ambiguous. Logically, the volunteers should be the ones pondering. Since both the main subject researchers and the pronoun they are in subject positions, parallelism suggests that they points to the subject researchers.* Between this choice and answer (A), answer (A) is better because the meaning is unambiguous.
The Correct AnswerCorrect answer (A) is a complete sentence and unambiguously indicates that the volunteers, not the researchers, are the ones who pondered ethical dilemmas. It also uses the correct idiom the basis for X is Y.
*
NOTE: the official explanation says that the pronoun they in answer (E) “must” point to researchers. However other official questions have used a subject pronoun to refer to a possessive noun, including the correct answer for #138 in the 2016
Official Guide for GMAT Review / #805 in the 2017
Official Guide. In the case of #138 / #805, no ambiguity exists because only one noun could possibly function as the antecedent. In the case of the Brain Scans problem, the two potential antecedents create the ambiguity.
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