Digging in sediments in northern China, evidence has been gathered

Question

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.

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

Here’s the sentence structure:

  • Digging in sediments in northern China, (Verb-ing modifier modifying the main subject)
  • evidence has been gathered by scientists (Main Subject – “evidence”; Main Verb – “has been gathered”)
    • suggesting that (Verb-ing modifier currently modifying “scientists”. Should logically modify “evidence”)
      • complex life-forms emerged much earlier than they had previously thought. (“clause” providing additional information about “suggesting” — suggesting what)

The sentence says that:

The scientists have gathered some evidence by digging in sediments in northern China. The evidence suggests that complex life forms emerged much earlier than previously thought.

The sentence has the following errors:

  1. The first blatant error is that the beginning modifier “digging” modifies “evidence”, meaning that the evidence was digging in sediments!
  2. “suggesting” (without comma) modifies the closest noun “scientists”, meaning that scientists suggest so. Logically, the evidence suggests so.
  3. The antecedent of “they” is not clear. Even though logically “they” should refer to “scientists”, structurally “they” seems to modify “life-forms”, producing an illogical meaning that these life-forms emerged earlier than these life forms had previously thought!!

Option Analysis

(A) Incorrect. For the errors described above.

(B) Incorrect. For the following reasons:

  1. Error no. 1 of the original sentence
  2. The use of past perfect “had been” is incorrect. There is no action in the simple past with which this action “previously thought” needs to be sequenced.

(C) Correct. All the errors in the original sentence have been rectified. Please observe that the structure “earlier than previously thought” is correct.

(D) Incorrect. “that which was previously thought” is incorrect. “that which” doesn’t stand for anything!

(E) Incorrect. “that” doesn’t refer to anything.

About Chiranjeev Singh

An Alumnus of IIM Ahmedabad and with scores 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 CJ@GMATwithCJ.com. He conducts online sessions for students across the world.

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