Sentence Correction

[gupta.akrati]

I have a doubt here.I had read in SC guide that when 'and' is preceded by a comma the following sentence must have a subject of its own but here in (C) we are not having any subject (they) after 'and'.

[ebernal]

I have a doubt here.I had read in SC guide that when 'and' is preceded by a comma the following sentence must have a subject of its own but here in (C) we are not having any subject (they) after 'and'.

C. "that local witnesses are difficult to locate, reticent, and"

This is a different situation. The word "and" signals a parallel marker and you should look for a list of things. Here that list of things describes what the local witnesses are. If there are only two things the correct structure is "x and y" the correct structure for a list of three things (in AC C) is "x, y, and z" - And these two or three things should be parallel Check it out in your MGMAT SC guide chapter 4 pg 53.

[gupta.akrati]

I have a doubt here.I had read in SC guide that when 'and' is preceded by a comma the following sentence must have a subject of its own but here in (C) we are not having any subject (they) after 'and'.

C. "that local witnesses are difficult to locate, reticent, and"

This is a different situation. The word "and" signals a parallel marker and you should look for a list of things. Here that list of things describes what the local witnesses are. If there are only two things the correct structure is "x and y" the correct structure for a list of three things (in AC C) is "x, y, and z" - And these two or three things should be parallel Check it out in your MGMAT SC guide chapter 4 pg 53.

thanks for the reply :)
I got the underlying concept.

[RonPurewal]

I have a doubt here.I had read in SC guide that when 'and' is preceded by a comma the following sentence must have a subject of its own but here in (C) we are not having any subject (they) after 'and'.

the poster above (below yours) has done a nice job of explaining what is actually going on in this particular instance.

however, note that this whole idea of "comma + andmust be used to connect to complete sentences" isn't really true.
you can use comma + and to connect smaller sentence elements, especially in cases where those elements are long enough to make the sentence unreadable without the extra punctuation.

for instance:

i closed the windows and locked the doors
--> everything here is short and easy to read, so there is no reason to add another comma before "and".

i closed the windows to keep the humidity and mosquitoes from entering the house, and locked the doors so they would not swing open by surprise.
--> the comma is desirable here -- even though it's not technically necessary -- because the sentence is extremely difficult to read without it; the two verb phrases are so long as to make a giant jumble of words if they are not broken up with some extra punctuation.