Hi,
complete and consistent theory of quantum gravity is singular. So, it should be followed by 'has'.
D,E are out.
Dr.Rajesh is the subject for the entire sentence. So, have is incorrect in C.
Moreover A and C are incorrect because comma+and can only join two independent clauses.
B correctly uses participle 'concluding' to modify the preceding clause.

Hence, B

OA please?

Mixed between A and B. what is OA?

I agree with Frankenstein for removal of C, D and E
Now for A and B.

After removing modifiers and phrases.....Dr Rajesh Gopakumar, has researched... and has concluded....

A is parallel, so A is correct.

I didn't understand "concluding" is modifying what ?

That is correct. A indeed is the OA.

dadu wrote:That is correct. A indeed is the OA.

Frankenstein i just thanked you for the comma thingy . i guess i need to withdraw my thanks . Could someone add a button

dadu wrote:That is correct. A indeed is the OA.

Hi,
I still don't understand this. I am pretty sure comma shouldn't be used when the sentence means something like this:
Dr.Rajesh has researched... and has concluded because the part after 'comma + and' doesn't have subject and hence cannot be an independent clause.
comma+and can be even used to state a list of things. This is not the case here.
Could you post OE and source.

Frankenstein i just thanked you for the comma thingy . i guess i need to withdraw my thanks . Could someone add a button

Even I don't know how to do this. Perhaps, you should PM Eric/site admin.

So this question leads to another inevitable question . Source ?

Frankenstein wrote:

dadu wrote:That is correct. A indeed is the OA.

Hi,
I still don't understand this. I am pretty sure comma shouldn't be used when the sentence means something like this:
Dr.Rajesh has researched... and has concluded because the part after 'comma + and' doesn't have subject and hence cannot be an independent clause.
comma+and can be even used to state a list of things. This is not the case here.
Could you post OE and source.

Frankenstein i just thanked you for the comma thingy . i guess i need to withdraw my thanks . Could someone add a button

Even I don't know how to do this. Perhaps, you should PM Eric/site admin.

Does the GMAT still test on Punctuation . You have any idea whether the which clause is acceptable without a comma before it . AFAIK which is non essential and requires a comma. Can which be essential ?

mundasingh123 wrote: Does the GMAT still test on Punctuation . You have any idea whether the which clause is acceptable without a comma before it . AFAIK which is non essential and requires a comma. Can which be essential ?

Hi,
I don't know much about punctuation being tested or not. But, when FANBOYS are used, using or not using comma is tested at least in some of the practice questions I have come across.
Well, coming to this particular question, you can refer to MGMAT Page-190, the example of Earl. That should probably help you.
I have seen many instances of using which without comma in grammar books as well. But, I am not sure about it when it comes to GMAT. I believe the distinction between 'that' and 'which' is so subtle that we won't be required to select one of the two options, which solely differ by this usage.

Frankenstein wrote:

dadu wrote:That is correct. A indeed is the OA.

I still don't understand this. I am pretty sure comma shouldn't be used when the sentence means something like this:
Dr.Rajesh has researched... and has concluded because the part after 'comma + and' doesn't have subject and hence cannot be an independent clause.
comma+and can be even used to state a list of things. This is not the case here.

Let me double check the comma from the source (I have the hard copy and is not with me at this moment). I might have mis-typed (had to already edited the original sentence twice because of typos:().

But, I am pretty sure of the OA.

Could you check my post on
https://www.beatthegmat.com/subordinatio ... 89131.html

dadu wrote: Let me double check the comma from the source (I have the hard copy and is not with me at this moment). I might have mis-typed (had to already edited the original sentence twice because of typos:().

But, I am pretty sure of the OA.

Yeah, please double check your source for the comma in A. Please mention the source as well. I do want to work on authentic sources only!

has researched and has concluded implies they are two different activities. But it appears conclusion happens based on the research finding - they are not two different activities.

Therefore usage of 'concluding' is approrpiate.

Moreover, comma+and (as Frankenstein) mentioned is used for two independent clauses - not for two verbs with the same subject.

IMO B

dadu wrote:Dr. Rajesh Gopakumar, a theoretical physicist of International repute, has researched whether complete and consistent theory of quantum gravity has a stringy set of additional excitations, and has concluded that the prospects for pure 3d gravity to be consistent and complete appear dim.
(A) has a stringy set of additional excitations, and has concluded
(B) has a stringy set of additional excitations, concluding
(C) has a stringy set of additional excitations, and have concluded
(D) have a stringy set of additional excitations, and concluding
(E) have a stringy set of additional excitations, concluding

Please discuss.

IMO - A, 'has a stringy set....' and 'has concluded' -are parallel.