While they are a popular exotic pet, not only are pythons potentially

Question

Pack 9, Question 1 of 5:

While they are a popular exotic pet, not only are pythons potentially dangerous to humans if they are large enough,  they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing  the risk of meningitis and sepsis in children.

A. they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing
B. they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increase
C. also exposing their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, increasing
D. but also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia to increase
E. but also exposing their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing

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EMPOWERgmatVerbal · Accepted Answer

Official Explanation

While they are a popular exotic pet, not only are pythons potentially dangerous to humans if they are large enough,  they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing  the risk of meningitis and sepsis in children.

A.  they can also expose  their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia,  and increasing  
 B.  they can also expose  their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia,  and increase  
 C.  also exposing  their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia,  increasing  
 D.  but also expose  their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia  to increase  
 E.  but also exposing  their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia,  and increasing

A review of our answer choices shows a split between using “but also” or “they can also” to introduce the second part of our sentence. There is also a split in which verb form we should use (the verb or the -ing form).

When we see a sentence that has “not only” in it and answer choices that include “not only,” it is tempting to ignore everything else and focus only on those options that fit the most common idiom.  While “not only X, but also Y” is the most common form of the idiom, “not only X, also Y” is a valid format as well.  Many times, “not only, but also” sentences do not include a subject or verb after those words, so it might be tempting to immediately eliminate the choices that start with “they can,” but that could potentially be a mistake. Remember, with “not only, also/but also” constructions, parallelism is key. So we need to start by looking at the portion of the sentence that isn’t underlined:

While they are a popular exotic pet,  not only are pythons  potentially dangerous to humans if they are large enough,  they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing  the risk of meningitis and sepsis in children.

The sentence reads “not only are pythons potentially dangerous to humans . . .” The structure is “not only” + a verb + the subject. When “not only” is followed by a verb and a subject, then the second clause (the also/but also clause) must also have a verb and subject. Because the verb and subject are not introduced  before  the “not only,” then the “also” clause must include those as well. While the order is not identical (in the second clause the verb and subject will come before the “also”), the parallelism is still apparent because each clause has the same components.

A. they can also expose their owners  to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing
 B. they can also expose their owners  to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increase
 C. also exposing their owners  to multiple pathogens, including salmonella, leptospirosis, and chlamydia, increasing
 D. but also expose their owners  to multiple pathogens, including salmonella, leptospirosis, and chlamydia to increase
 E. but also exposing their owners  to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing

We can eliminate options C, D, and E because they do not have a verb and subject. (“Their owners” is the object of the verb expose, not the subject.). In fact, Options C and E don’t even have a verb! An -ing verbal without a helping verb cannot act as a verb, so “exposing” is not a verb.

Beyond the parallelism of “not only, but also,” we need to consider parallelism for the sentence as a whole. The verb in the non-underlined portion is “are dangerous.” This parallels “can expose.” The last verb form choice is “increase” or “increasing.” What is parallel to “dangerous” and “expose”? Increase!  Option A uses “increasing,” which is not parallel. It cannot be the best answer.

We have successfully eliminated four answer choices. Option B is the best answer.

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shameekv1989 · Answer

While introduces a subordinate clause, hence we need a main clause in the sentence. Thus the use of "they can also" to introduce a main clause is appropriate as against "but also" which will also be redundant as the use of "but" and "while" is not warranted together.

We need the following sentence structure :-
While X, not only are (verb), they can also expose (verb).... and increase (verb)

"Also" has to be followed with whatever followed "not only" - in this case a verb.

Moreover "expose" and "increase" needs to be parallel.

A - Not parallel in the use of "expose" and "increasing" 
 B - Correct -  not only are X, they can also Y and Z  - where X, Y and Z are verbs 
 C - "also exposing" not parallel to "not only are" 
 D - "expose to increase" shows intention which is not the intended meaning. 
 E - "but also exposing" is not parallel to "not only are"

DasAshish1 · Answer

B ? 
We need the subject with also because post not only subject is there in an inverted structure. So to maintain parallelism we need a subject with also ..

So C D E OUT. 
Out of A and B. B maintain parallelism with verb expose and Increase

jrk23 · Answer

While they are a popular exotic pet, not only are pythons potentially dangerous to humans if they are large enough, they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing the risk of meningitis and sepsis in children. 
 
A. they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing- Pathogens can do two things one is expose and another is increase the risk, so the use of increasing is not correct 
B. they can also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increase- I think its correct 
C. also exposing their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, increasing- no Main clause 
D. but also expose their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia to increase- to increase is wrong 
E. but also exposing their owners to multiple pathogens, including salmonella, leptospirosis, and chlamydia, and increasing.- no independent clause

correct me if i am wrong

Tushrgupta · Answer

I will choose B
Concept tested 
1. Not only requires another "clause" to complete 
1. Modifier ing will not form a clause (Option C,E)
 if "and" is used before modifier the cause and result relationship is lost.The first ing modifier becomes parallel to the 
 second Option (A,E)
 2. Gerund to verb is used to show intention(option D it is not the intention of pythons but the result )
 3. Idiom Not only ....But also/Not only .....but/Not only.....also.....

EMPOWERgmatVerbal · Answer

Well done, shameekv1989 ! You cracked the code on this one! We also like that you color-coded things so they're easier to see.

Kudos to you!

EMPOWERgmatVerbal · Answer

Well done, DasAshish1 ! You cracked the code on both the idiom structure and parallelism issues.

EMPOWERgmatVerbal · Answer

No need to correct you jrk23 because you're not wrong! Great job, and kudos to you!

EMPOWERgmatVerbal · Answer

Well done, Tushrgupta ! You cracked the code! We're looking forward to seeing more great explanations in future questions!

gvij2017 · Answer

In extension of your explanation, does comma before "including" essential? In my understanding it is not required generally but when we have long list of items, we can use comma before including or such as. Is it correct?

VerbalBot · Answer

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While they are a popular exotic pet, not only are pythons potentially

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While they are a popular exotic pet, not only are pythons potentially

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