Sentence Correction

Sixty-five million years ago, according to some scientists, an asteroid bigger than Mount Everest slammed into North America, which, causing plant and animal extinctions, marks the end of the geologic era known as the Cretaceous Period.

A) which, causing plant and animal extinctions, marks
B) which caused the plant and animal extinctions marking
C) and causing plant and animal extinctions that mark
D) an event that caused plant and animal extinctions, and it marks
E) an event that caused the plant and animal extinctions that mark

I could not choose between D and E. Please explain the rationale for choosing between the two. Thanks.

A and B are incorrect - which refers to North America; C is also not correct "and causing"...should be caused.

[spoiler]OA-E : Why not D?[/spoiler]

I think because D has "it" and we dont know what it refers to. america or asteroid or extinction????

Preeti

even i was confused b/w D and E but on further analysis i found E more appealing coz..
a) in D 'it' has no proper antecedent.
b) in E the 2nd that clearly connects the extinction and the end of era...it shld the extinction, not event or asteroid, which marked the end of era.

hope this helps...

Preeti, you're right! Ambiguous 'it' is the reason why D is not correct. The sentence should refer back to the asteroid that hit earth, also referred to as 'the event'. This event caused plant and animal extinctions, and those mark the end of the cretaceous or whatever.

Final solution at one place:

Important: The purpose of this post (and all the other posts by me) is to give a complete solution to all GMAT-Prep Verbal questions at one place. Sometimes students have to wade through dozens of posts to get to the final answer. My posts will give one complete and crisp solution required to arrive at the correct answer by eliminating the wrong one. Some of the content in these posts may have been taken from various other sources (discussion forums).

Sixty-five million years ago, according to some scientists, an asteroid bigger than Mount Everest slammed into North America, which, causing plant and animal extinctions, marks the end of the geologic era known as the Cretaceous Period.
(A) which, causing plant and animal extinctions, marks
(B) which caused the plant and animal extinctions marking
(C) and causing plant and animal extinctions that mark
(D) an event that caused plant and animal extinctions, and it marks
(E) an event that caused the plant and animal extinctions that mark

This sentence is about the use of an abstract noun (usually a new word that is not given in the original option) to refer to the entire preceding clause. Such a construction is almost always considered correct on the GMAT. So, most probably, we have to choose between D and E (both contain a new noun 'an event' after the comma) . Read more about abstract noun constructions below.

As per meaning clarity, the event (the slamming of the asteroid) didn't mark the end of the geologic era; rather the extinctions marked the end of the era (logical).

Also, A and B use the word 'which' ... the word 'which' is a pronoun, so it can refer only to a noun. But in these options, the word 'which' tries to go back to 'slammed (verb)' ... WRONG.

In C, and 'slammed' and 'causing' are not parallel.

In D, 'event' refers to the 'slamming' and 'it' refer to the event (and so to 'the slamming') ... wrong meaning. Also, D is not parallel (that caused and it marks). Also, the comma usage is wrong in D.

E corrects the meaning: 'extinctions that mark' ... the word 'that' refers to the 'extinctions'. Perfect.

Correct: E

Abstract nouns modifying the entire preceding clause (after a comma)

(If you have an appositive modifier that's an abstract noun - such as "strategy", "figure", "statistic", "findings", "situation", "change", "difference", etc. - then such an appositive may be allowed to describe the entire situation described in the previous clause.)

1. I only have one onion, a deficiency that will make it impossible to cook this dish.

2. The scientists discovered whale-fish bones in the Arctic, findings that prove the existence of whale-fish.

3. Scientists have found high levels of iridium in certain geographical formations around the world, results that suggest the cataclysmic impact of a meteor millions of year ago.

4. An asteroid bigger than Mount Everest slammed into North America, Sixty-five million years ago, an event that caused the plant and animal extinctions that mark the end of the geologic era known as the Cretaceous Period.

5. The coach tried to put 5 receivers on the line, a strategy that failed.

6. X observed large concentrations of metals in the sediments, findings consistent with the history of deposits in the region.

7. Recent studies have shown that X is 60 percent of Y, a finding that has shocked many in the scientific community. OR Recent studies have shown that X is 60 percent of Y, a statistic that has shocked many in the scientific community.

8. Neanderthals had a vocal tract resembling an ape's and so were probably without language, a shortcoming that may explain why they were supplanted by our own species.

9. Scientists have observed large concentrations of heavy-metal deposits in the upper twenty centimeters of sediments from the Baltic Sea, findings consistent with the growth of industrial activity in the area.

10. I went to the bar with John Smith, an excursion that was much more fun than working all night.

11. The general tried to get his troops to retreat before being surrounded, a strategy that ultimately failed.

Such abstract noun constructions are preferred on the test ... almost always correct.