Some bat caves, like honeybee hives, have residents that take on diffe

Question

Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance,  acting as sentinels and to sound  a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.

(A) acting as sentinels and to sound

(B) acting as sentinels and sounding

(C) to act as sentinels and sound

(D) to act as sentinels and to sound

(E) to act as a sentinel sounding

https://www.nytimes.com/1984/11/27/science/the-world-of-bats-scientists-uncloak-the-myths.html

Some bat caves, like honeybee colonies, have residents that take on different duties such as guarding the entrance,  acting as sentinels and sounding  a vocal alarm at the approach of danger, and scouting outside the cave for new food and roosting sites.

The only option looks right to me is B. It is the OA indeed.
However, my question is what "sounding" functions as? It can't be the parallelism of "acting" and " scouting" because of 2 "and" preceded "sounding" and "scouting". Therefore it must be a noun and parallel with "sentinels". 
But IMO, an article is needed ("a sounding") or the plural should be used ("soundings"). 
We can't say "My properties include houses and  CAR  =>IMO: "My properties include houses and cars (or a car)" is better.
What do you think?
Thanks.

daagh · Accepted Answer

This is a test of list parallelism, made tricky by mixing up with pseudo parallels

Th basic theory of list parallelism stipulates that it is important to identify the elements of the series first. Within each series, the last factor is always preceded by the word “and” which marks the end of the series. 
If there are more than one series, then the last series by itself has to be again preceded by another “and”. 
If there are more than one series in a passage, ensure that each of the series maintains its own parallel structure within its domain.

In the given text, we have two series.
1. One is the ‘defending’ series that includes acting as sentinels and sounding a warning
2. The other is the ‘scouting’ series that includes searching for new food and roosting

These two arms must be separated by an ‘and’; all choices do that and so no issue about it. 
But it is the parallelism within each series that is presenting a problem here. As you may see, 
Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and to sound a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.

(A) Acting as sentinels and to sound --- acting and to sound is not parallel in the first series. 
(B) acting as sentinels and sounding – perfect parallelism -- correct choice 
(C) to act as sentinels and sound --- The infinitive spoils the parallelism since, the first duty is marked as defending and the other duties must also be in the same ing form rather than in infinitive form
(D) to act as sentinels and to sound --- same as C
(E) To act as a sentinel sounding --- same as C and D

mikeCoolBoy · Answer

sounding here is a present participle that modifies the previous clause "residents that take on different duties such as defending the entrance"

read the second part this way

residents that take on different duties such as  defending  the entrance,  acting as sentinels and sounding a warning at the approach of danger , and  scouting  outside the cave for new food and roosting sites

defending is parallel to scouting

acting and sounding are parallel to each other and modify "defending the entrance". How do the residents defend the entrance? acting as sentinels and sounding a warning at the approach of danger.

Let me know if this helps.

elevinty · Answer

I'll go with A (I dont know what the hell I was thinking in my initial post)
A to act as a guardian sounding 
 Between A and C, the decision of which one to choose depends on logic, are the doctors who are monitoring have two duties (which guarding and sounding) or only one duty that is guarding(and the only duty for the guard is to sound a warning) I would think the latter, otherwise what are they janitors guarding the hospital from I dont know thieves.  
B to act as guardians and to sound 
C to act as guardians and sound 
 There is no difference between B and C, both of them have the same structure 
D acting as guardians and to sound 
 There is no way this can be the right answer, because of the presence of the AND both Sound and act has to be parallel, and you cant parallel infinitive with a participle even if they were both NOUNS or ADJECTIVES. 
E acting as guardians and sounding 
 If you want to parallel MONITORING with ACTING, SOUNDING and RECEIVING then the AND before SOUNDING shouldn't exist.

egmat · Answer

We recently created a video solution for this question. For more video solutions, log in to your e-GMAT account and go to OG Verbal Solutions course.

[vimeo]https://vimeo.com/32296672[/vimeo]

Darmody · Answer

Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance,  acting as sentinels and to sound  a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.

(A) acting as sentinels and to sound
(B) acting as sentinels and sounding
(C) to act as sentinels and sound
(D) to act as sentinels and to sound
(E) to act as a sentinel sounding

Hi guys, can somebody explain the parallel construction A, B and C, and D ? Isn't it a little bit awkward and wrong ? In which case can we have a list with two "and" ?

Thx !

Vercules · Answer

Hi Darmody,

Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance,  acting as sentinels and to sound  a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.

(A) acting as sentinels and to sound

Changes the meaning by changing the list

(B) acting as sentinels and sounding

Correct, maintains parallel structure in all the lists

(C) to act as sentinels and sound
 
Changes the meaning; sentence now implies that they defend to act as sentinels and sound...

(D) to act as sentinels and to sound

Same as C

(E) to act as a sentinel sounding

Again changes the meaning; moreover "sentinel" should be plural as "residents" is plural.

The correct answer choice (B) presents the list with parallel structures. I have marked the lists by brackets in the correct version of the sentence.

Some bat caves, like honeybee hives, have residents that take on different duties such as (defending the entrance, acting as (sentinels and sounding a warning at the approach of danger), and scouting outside the cave (for new food and roosting sites)).

The best way to find out the lists is by the meaning differences between them.

for example

In sports I like ((football, baseball and table tennis), and in music I like (Rock, Jazz and Classical)).

In GMAT whenever you see "and" you should check for the logical lists and make sure the structures being listed are parallel grammatically.

Hope it helps,

Vercules

Darmody · Answer

Hi thx for that, one last question, in "acting as (sentinels and sounding a warning at the approach of danger) ", if I understand what you say, "sentinels" and "sounding a warning at the approach of danger" should be parallel shouldn't they ? But it does not seem to make any sense, as the sentence "acting as sounding a warning at the approach of danger" has no meaning. Did I understand it wrong?

Vercules · Answer

Hi Darmody,

I can understand your concern. The correct answer choice is not a well constructed sentence and looks a little weird. But, it is the least bad among all the answer choices. The other choices are clearly wrong because almost all of them are changing the intended meaning of the sentence.

If you break the sentence; defending the entrance, acting as sentinels and defending the entrance, sounding a warning at approach of danger.

ie. by acting and sounding they are defending the entrance.

Consider an example similar in structure:

John is defending his position, acting as a lawyer and presenting a sound argument that he is not guilty.

John is defending his position in two ways

i) by acting as a lawyer
ii) by presenting a sound argument

One more similar example

By doing his job properly, acting as a role model and creating a conducive environment  for the whole team, John has become the most admired manager in the company.

Tip: Concentrate more on errors in sentence correction; it is far more easier to prove that a choice is incorrect than to prove that it is correct. In your practice try to get familiar with the error patterns that sentence correction questions test.

Moreover, SC 1000 is not a very reliable source for practice. First it is quite old and contains short questions like this one, while in these days longer sentences are seen in SC in GMAT, second most of the questions are good but the bad ones could really screw up your concepts. Do it if you have exhausted all the official stuff at your disposal.

Hope it helps,

Vercules

yodeepak · Answer

Hi, My doubt here is that what is the parallel list here? Option 1 or Option 2?
 Option 1: 
1)defending 
2)acting and sounding
3)scouting

Option 2: 
1)defending 
2)acting 
3)sounding
4)scouting

Why do we need 'and' between acting & sounding when these are parallel to other 2 items in the list?

Or in other words  what's wrong with this sentence -

Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance,  acting as sentinels, sounding a warning at the approach of danger , and scouting outside the cave for new food and roosting sites.

CrackverbalGMAT · Answer

Hi Deepak

None of your options is correct.

Structure is 
1 defending, (acting.. and sounding),
and
2 scouting

E is clearly wrong because of parallelism issue. Rest all options have 'and' and hence we need to look for a valid construction.

'defending, acting, sounding and scouting ' - is NOT one of the options

Also, note the 'comma' before 'and scouting'. This separates 'acting and sounding' from 'defending and scouting'.

'defending , acting... and sounding...  , and scouting'

"acting as sentinels and sounding..danger" is describing the act of 'defending the entrance'.

Hope this helps!
Dolly Sharma
Verbal Trainer
CrackVerbal

GMATNinja · Answer

A question from our  sentence correction "ask me anything" thread :

Before we get into the weeds with grammar terminology, let's take an intuitive, non-technical look at the words in bold:

Some bat caves, like honeybee hives, have residents that take on  different duties such as   defending  the entrance,  acting  as sentinels and  sounding  a warning at the approach of danger, and  scouting  outside the cave for new food and roosting sites.

All four of these words are doing the same thing, right? Each is a duty that can be taken on by the residents of the bat caves. So as a starting point, it makes sense that they could all be in the same grammatical form, since the residents do all four of those things (defending the entrance, acting as sentinels, sounding a warning, and scouting for food). So even if you don't think about the technicalities of grammar and parallelism at all, you might decide that this seems acceptably parallel, and move on.

If you do want some jargon: all of those four words (defending, acting, sounding, scouting) are gerunds, which is a fancy way of saying that they're "-ing" words that function as nouns. (More on "-ing" words in  this article .)

And it wouldn't make sense for "sentinels" and "sounding" to be parallel to each other: "... acting as   sentinels  and  sounding  a warning..." If the two words in bold were parallel, then the sentence would be saying that the residents "act as sentinels" (which makes sense) and "act as sounding a warning" (which makes no sense). (More on parallelism in  this video  if anybody wants a basic refresher.)

Finally, you might be wondering why the word "and" appears so many times in the correct answer. I don't have a very satisfying answer to that, to be honest. In a sense, "acting as sentinels" and "sounding a warning" are all part of the same duty: "sounding a warning" is part of what the residents must do if they're "acting as sentinels." So those two activities are separated by their own "and", but they're still part of the larger structure of parallelism in the sentence ("defending..., acting and sounding..., scouting...").

I hope this helps!

CrackverbalGMAT · Answer

This question tests  Parallelism .

Once we identify the items in the list that must be parallel, we can easily eliminate one option after another.

Now, what is the question saying?

That bats have duties such as  defending …, <which includes>  acting …, and  sounding … 
Here, 'acting... and sounding...' is modifying 'defending'.

Let’s look at the options:

(A) acting as sentinels and  to sound

(B)  acting  as sentinels and  sounding

(C)  to act  as sentinels and sound

(D)  to act  as sentinels and to sound

(E) to act as a sentinel  sounding

Eliminate Options A, C, D, and E.

Option B  is the best choice.

Hope this helps!

VerbalBot · Answer

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Some bat caves, like honeybee hives, have residents that take on diffe

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GMAT Sentence Correction (SC - EA only) Questions

Some bat caves, like honeybee hives, have residents that take on diffe

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