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GMAT Verbal

GMAT Verbal Question of the Day

Practice GMAT Verbal with the production-style question-of-the-day selection for this public URL.

Question 1

While global temperatures have risen sharply over the last century, they have only recently eclipsed the Medieval period, during which scientists theorize that a series of volcanic eruptions sent the earth into a period of historic warmth.

  1. they have only recently eclipsed the Medieval period, during which scientists theorize that a
  2. they have only recently eclipsed those of the Medieval period, during which scientists theorize that a
  3. it has only recently eclipsed the Medieval period, during which, scientists theorize, a
  4. it has only recently eclipsed that of the Medieval period, during which scientists theorize a
  5. they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a
Explanation: This problem provides two very clear decision points for you to get started:
  1. "they" vs. "it" as the first word of the sentence
  2. "that of" vs. "those of" vs. (no possessive) in relation to "the Medieval period"
The key to both of these is recognizing the subject of the sentence which is "global temperatures." Since temperatures is plural, the pronoun that corresponds to them must be "they" and you can eliminate choices "it has only recently eclipsed the Medieval period, during which, scientists theorize, a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a". Then notice that the comparison is between current global temperatures and the temperatures during the Medieval period; you cannot logically compare "temperatures" with the timeframe, so you need to have "those of" (which "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "it has only recently eclipsed that of the Medieval period, during which scientists theorize a" have but "they have only recently eclipsed the Medieval period, during which scientists theorize that a" does not) to properly draw the comparison. Between "they have only recently eclipsed those of the Medieval period, during which scientists theorize that a" and "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a", notice that the only difference is commas around "during which." Why is that important? Here you're dealing with a tense/timeline decision. Since "theorize" is present-tense but the Medieval period is clearly in the past (even if you're not a historian, the fixed past tense "sent" outside the underline tells you that those volcanoes were in the past), you cannot have "scientists theorize" as part of the phrase "during which." The scientists currently theorize that volcanoes caused the global warming, so you need to separate that subject-verb from the modifier "during (the Medieval period)." This means that answer choice "they have only recently eclipsed those of the Medieval period, during which, scientists theorize, a" is correct.