To screen women for colorectal cancer, the use of either colonoscopy

Question

To screen women for colorectal cancer, the use of either colonoscopy  or flexible sigmoidoscopy is acceptable although a recent study shows that this  is the preferred method.

A. or flexible sigmoidoscopy is acceptable although a recent study shows that this

B. and flexible sigmoidoscopy is acceptable although a recent study shows that colonoscopy

C. or performing flexible sigmoidoscopy is acceptable although a recent study shows that the former

D. or flexible sigmoidoscopy is acceptable although a recent study shows that the former

E. or flexible sigmoidoscopy is an acceptable method although a recent study shows that colonoscopy

Bunuel · Accepted Answer

OFFICIAL EXPLANATION

To screen women for colorectal cancer, the use of either colonoscopy  or flexible sigmoidoscopy is acceptable although a recent study shows that this  is the preferred method.

A. or flexible sigmoidoscopy is acceptable although a recent study shows that this

Incorrect.

This answer choice is stylistically flawed. The pronoun  this  is ambiguous because it can refer to more than one singular noun which preceded it ( colonoscopy  or  flexible sigmoidoscopy ).

What helps us identify this question as a Pronoun question as well as identify the Ambiguity mistake is the following Stop Sign: Every pronoun in the underlined part of the sentence or after it

It is true that stylistic mistakes are not always corrected. However, since there is an answer choice that does address the issue of Ambiguity, it is preferable to this one.

B. and flexible sigmoidoscopy is acceptable although a recent study shows that colonoscopy

Incorrect.

This answer choice is grammatically incorrect.  Either  must be followed by  or , not  and .

What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign: (n)either... (n)or...

C. or performing flexible sigmoidoscopy is acceptable although a recent study shows that the former

Incorrect.

Although this answer choice eliminates the Ambiguity of the original sentence, it is grammatically incorrect. The same part of speech that follows  either  must also follow  or .  Either  is followed by the noun  colonoscopy .  Or , however, is followed by the verb  performing .

D. or flexible sigmoidoscopy is acceptable although a recent study shows that the former

This answer choice eliminates the ambiguity in the original sentence by the addition of the word  former . It also makes correct use of the structure  either...or .

E. or flexible sigmoidoscopy is an acceptable method although a recent study shows that colonoscopy

Incorrect.

Although this answer choice corrects the ambiguity created by the original sentence, it is not the most concise of the answer choices.

Sumi1010 · Answer

To screen women for colorectal cancer,  the use of  either  colonoscopy  or  flexible sigmoidoscopy  is   acceptable although a recent study shows that  this  is the preferred method.

The above sentence has singular subject "the use" and hence "is" is correct verb. 
 A recent study shows that THIS is preferred method.  
Two problems here.
- We don't have clear antecedent of "this". It could be colonoscopy or flexible sigmoidoscopy. 
- THIS is a demonstrative pronoun and hence can't stand alone. It can be used as a noun modifier though. e.g. this method.

A. or flexible sigmoidoscopy is acceptable although a recent study shows that  this 
 Incorrect for above reasons. 
B.  and  flexible sigmoidoscopy is acceptable although a recent study shows that colonoscopy
 Either- should be followed by Or (not - and). 
C. or  performing  flexible sigmoidoscopy is acceptable although a recent study shows that the former
   The use either X OR Y  - is correct. Incorrect construction here :  The use either X Or performing Y.  
D. or flexible sigmoidoscopy is acceptable although a recent study shows that the former
 Correct. Former stands for colonoscopy.  
E. or flexible sigmoidoscopy is an  acceptable method  although a recent study shows that colonoscopy
   The use of either X or Y is an acceptable method.   - "the use" can't be a method !!

Hence,  D

winterschool · Answer

To screen women for colorectal cancer, the use of either colonoscopy or flexible sigmoidoscopy is acceptable although a recent study shows that this is the preferred method.

A. or flexible sigmoidoscopy is acceptable although a recent study shows that  this   Incorrect

antecedent of this is not clear

B.  and  flexible sigmoidoscopy is acceptable although a recent study shows that colonoscopy  Incorrect

and uses wrong

C. or  performing  flexible sigmoidoscopy is acceptable although a recent study shows that the former  Incorrect

parallelism error - ...........either colonoscopy or performing..................
colonoscopy and performing are not paraelle

D.  or flexible sigmoidoscopy is acceptable although a recent study shows that the former   Correct 
 
E. or flexible sigmoidoscopy is  an acceptable method  although a recent study shows that colonoscopy  Incorrect

within an acceptable method the former cant be preferred method

To screen women for colorectal cancer, the use of either colonoscopy

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GMAT Sentence Correction (SC - EA only) Questions

To screen women for colorectal cancer, the use of either colonoscopy

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards