The new house's front door is secured by an electronic lock; a feature

Question

The new house's front door is secured by an electronic lock;  a feature that not only allows residents to lock and unlock the door without physical keys, but also may prevent  them from entering the house during a power outage.

(A) a feature that not only allows residents who lock and unlock the door without physical keys, but also may prevent

(B) a feature allowing residents without a physical key to lock or unlock the door, but also possibly preventing

(C) a feature allows residents locking or unlocking the door without physical keys, but also possibly preventing

(D) this feature allows residents to lock and unlock the door without a physical key, but may also prevent

(E) this feature not only allows residents without physical keys to lock or unlock the door, but also prevents

daagh · Accepted Answer

A semicolon should be followed by a free standing but related clause. One can dump the first two options simply on that grammar as what follow the semicolon are simple noun phrases and not verbed clauses. C is guilty of using unparallel symmetry around ‘but’. 
E misuses the correlative conjunction ‘not only … ‘but also’ in its intent. Not only but also is used between two same direction phenomena with emphasis on the latter. It cannot be used between two paradoxical situations. E says a positive thing in the first arm but indicates a negative factor in the second. D is the best as many have pointed out for various other reasons.

akashb106 · Answer

a) a feature that  not only allows  residents who lock and unlock the door without physical keys,  but also may  prevent---  Not Only, But also is not parallel.  
b) a feature allowing residents without a physical key to lock or unlock the door,  but also  possibly preventing---  Incorrect, Not only is missing in the sentence. Incorrect idiom.  
c) a feature allows residents locking or unlocking the door without physical keys,  but also  possibly preventing---  Same as B 
d)  this feature allows  residents to lock and unlock the door without a physical key,  but may also prevent ---  Correct. Although it does not use Not only, But also. But it is the best and most parallel answer choice.  
e) this feature not only allows residents without physical keys to lock or unlock the door,  but also prevents ----  Changes meaning. The omission of may changes meaning.

Narenn · Answer

Choice A should be same as the underlined part of the sentence. Here, in choice A, lock is preceded by 'who' where as, in the underlined part of the sentence, lock is preceded by 'to' . So this creates confusion. Here I am assuming the wording of Choice A and posting my answer in light of that. Answer should be D A) INCORRECT :- The ideal structure is Not only x...... but also y...... , in which you should have something concrete x that follows not only . In this choice who lock and unlock the door without physical keys is the relative clause modifying the noun residents . If we ignore this modifier we would left with a feature that not only allows residents....................., but also may prevent them................ . Since there is nothing that describes what is not only , this structure does not make sense. B) INCORRECT :- This choice has the modifier issue. without a physical key should logically modify the lock or unlock the door , but here, because of its wrong placement, it is modifying residents . Hence the sentence means that residents do not have the physical key. well we do not know this. C) INCORRECT :- With the structure but also possibly preventing we are introducing hypothetical situation that feature may prevent residents from entering the house during powercuts . In hypothatical mood infinitive form of the verb preferred over gerund form. D) CORRECT :- correct and concise structure. E) INCORRECT :- Incorrect for the same reason cited at Choice B. Hope that helps!

srinjoy28 · Answer

I am not getting why option E is wrong?
Another doubt as laveen put it....Can anybody please clarify...
Thanx in advance.....

Narenn · Answer

As for choice D, In the first phrase, the verb is in simple present tense, so we have to get the verb agree with subject ( feature.....allows ); however, in the second phrase, the verb is in future tense wherein   may   is functioning as an auxiliary verb. In this case the rules of subject verb agreement that we follow in simple present tense will not apply for this verb tense. i.e. Irrespective of Singular or Plural subject the verb will be in its simplest form.

feature   allows residents  ...................................................., but   feature may also prevent   them.......................

In Choice E, As cited in my earlier response, incorrect placement of modifier  with or without keys  changes the meaning of the sentence.

Hope that helps!

dabaobao · Answer

Official Solution (Credit: Manhattan Prep)

This sentence describes two effects of the electronic lock: one advantage (residents can lock and unlock the door without a physical key) and one disadvantage (they may not be able to get into the house when the power is out).
 
(A) The portion of this choice following the semicolon is a fragment, consisting only of a feature and modifiers. The idiom not only X but also Y is used to indicate that two ideas reinforce each other; its usage doesn’t make sense for two contrasting ideas.
 
(B) The portion of this choice following the semicolon is a fragment, consisting only of a feature and modifiers. The modifier without physical keys is misplaced; the point is that the residents can lock and unlock the door without using a key, not (as this choice implies) that residents without keys can lock and unlock a door by some other, unexplained means.
 
(C) Allows residents locking or unlocking is unidiomatic; the sentence should say allows residents to lock or unlock. Allows residents is not parallel to preventing them. 
 
(D) CORRECT. This choice contains complete sentences before and after the semicolon, as required. This feature is correctly used to refer to the immediately preceding electronic lock. The use of but (also), without not only, correctly indicates the contrast between the two parallel elements. Allows and may prevent are parallel.
 
(E) The idiom not only X but also Y is used to indicate that two ideas reinforce each other; its usage doesn’t make sense for two contrasting ideas. The modifier without physical keys is misplaced; the point is that the residents can lock and unlock the door without using a key, not (as this choice implies) that residents without keys can lock and unlock a door by some other, unexplained means.

verma8670 · Answer

Can anyone explain why the use of 'prevent' is correct for a singular thing 'this feature'. shouldn't it be right to use 'prevents'?

headofthetable · Answer

Before I give a 10 second answer, please bear in mind that the idiom Not only....But also is used for lists in one/same direction.

For eg - Jim is not only handsome but also intelligent - CORRECT

For eg - Jim is not only humble but also insensitive - WRONG....Makes no sense. Humility and insensitivity are not related.

Coming back to the question

The new house's front door is secured by an electronic lock;  a feature that not only allows residents to lock and unlock the door without physical keys, but also may prevent  them from entering the house during a power outage.

(A) a feature that not only allows residents who lock and unlock the door without physical keys, but also may prevent --- INCORRECT IDIOM USE : first item is a useful feature but second item is a disadvantage

(B) a feature allowing residents without a physical key to lock or unlock the door, but also possibly preventing --- awkward. Does the feature work for all residents OR only for the ones without a physical key... Hmm

(C) a feature allows residents locking or unlocking the door without physical keys, but also possibly preventing ---- PARRALLELISM ISSUE : allows and preventing

(D) this feature allows residents to lock and unlock the door without a physical key, but may also prevent------ || and make sense. PLEASE NOTE we have not used NOT ONLY...BUT ALSO idiom here (for that the items should be in a single direction)

(E) this feature not only allows residents without physical keys to lock or unlock the door, but also prevents --- INCORRECT IDIOM USE : first item is a useful feature but second item is a disadvantage

mavelous · Answer

Hi,

As discussed above, the first three options fall out simply because of the semicolon and the modifier-sounding second clause.

Between d) and e), there's no SV agreement issue between "this feature" and the "prevent" variants.

d)  this feature  allows residents to lock and unlock the door without a physical key, but  may  also  prevent  (.. may prevents is not correct use)
e)  this feature  not only allows residents without physical keys to lock or unlock the door, but also  prevents

it's the intended meaning that is distorted in e) that helps eliminate this choice.

mavelous · Answer

At first, I thought that "not only... but also" in the E might be talking about two disadvantages, and could eliminate for certain because this choice changes the certainty to "but also prevents", whereas the original prompt has a lower "may prevent" eventuality.

back to the advantage/disadvantage, slyly constructed red herring from MGMAT )))
You could interpret "residents without physical keys" as intruders / unauthorized access (therefore disadvantage), as well as the inconvenience during power outages.
whereas in original, "unlock without using a physical key" is an advantage as in hassle-free, smart home (for authorized access).

kprabha · Answer

Looking at the meaning this option does look good. But isn't option D has a S-V agreement error ?
 this feature  allows residents to lock and unlock the door without a physical key, but may also  prevent

This feature is singular and uses singular verb in the first part but uses plural verb "prevent" in the second part.

VerbalBot · Answer

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

The new house's front door is secured by an electronic lock; a feature

Prep Toolkit

Top 5 GMAT Debrief Videos

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

GMAT Sentence Correction (SC - EA only) Questions

The new house's front door is secured by an electronic lock; a feature

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