Sentence Correction

Some bat caves, like honeybee hives, have residents
that takeon 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
(El to act as a sentinel sounding

OA is B .

My question is related to participle parallelism.

Correct Sentence Structure is : different duties such as W, X and y, and Z. i found this structure somewhat odd because of two and.

Please let me know the reasoning for such structure and how to identify such structure in case it is correct in GMAT exam.

Also i need to know is there any other way to write above sentence that contains only 1 AND.

i mean structure like X,Y and Z.


Thanks

you are not parsing the sentence correctly
there are only 2 duties that are mentioned --->defending the entrance and scouting outside the cave for new food and roosting sites.

in the structure :defending the entrance, acting as sentinels and sounding ---->the construction "acting as sentinels and sounding" is further explaining the process of defending !!

Hi Rich/Experts,

I have a question here. Is comma + verbing (acting as sentinels and sounding) modifying the noun defending by providing info how are they defending or are they 3 indep acts that are happening inside like you mentioned in option B.

However, if they are indeed acting as modifiers, then do we need ,and before the second action scouting.

Please clarify?

[email protected] wrote:Hi Rich/Experts,

I have a question here. Is comma + verbing (acting as sentinels and sounding) modifying the noun defending by providing info how are they defending or are they 3 indep acts that are happening inside like you mentioned in option B.

However, if they are indeed acting as modifiers, then do we need ,and before the second action scouting.

Please clarify?

Two different verb-ing usages.

1) clause, verbing in which "verbing" functions as a participle/adjective following a clause. Tim forgot to go to the store, angering his roommates. In this case, "angering" is a participle that modifies the subject of the previous clause, Tim. (Alternatively, one could say that "angering" is modifying the entire previous clause.)

2) verbing, verbing, and verbing: in which the verbings function as gerunds/nouns. I enjoy biking, swimming, and painting. Here we simply have a list of nouns. (They happen to be action nouns, so they feel a little verbier, so to speak.)

In this SC, we have an instance of usage 2.

(This case sounds a little odd as one of the three elements in the parallel construction contains a conjunction. In other words, the three duties are

1) defending the entrance

2) acting as sentinels and sounding a warning

3) scouting outside the cave

Thanks for your reply David.

Can I also say if comma+ verbing was indeed acting as a modifier (,acting and ,sounding) then it would be modifying the previous clause 'Some bat caves, have residents that take on different duties' instead of the phrase such as defending the entrance?

Please confirm?