Hi Sudhanshu,
I'm new to this game of GMAT, just started but would try answering.

Due to parallelism, we should have performing ....running (...defending), leaving us options B & C.

C- in my view does not have the correct grammar---endurance running swiftly......., so answer is B.

Why do you think B is correct?

reply2spg wrote:Source - Grockit

Professional Tennis players, similar to professionals in other sports, exhibit different strengths such as serving with seppd and accuracy, performing with endurance and run swiftly even late in match, and defending against tricky drop shots and lobs.

performing with endurance and run
performing with endurance and running
performing with endurance running
to perform with endurance and to run
to perform with endurance and run

OA B, IMO C

also dunnot understand why B is correct... and ...and...

Yes that is what my question is. Since you have 'performing with endurance and running' means list should end after 'and running'. But it is not correct, since list is continued in non underlined portion, in that case how come B is correct here?

Confused

diebeatsthegmat wrote:

reply2spg wrote:Source - Grockit

Professional Tennis players, similar to professionals in other sports, exhibit different strengths such as serving with seppd and accuracy, performing with endurance and run swiftly even late in match, and defending against tricky drop shots and lobs.

performing with endurance and run
performing with endurance and running
performing with endurance running
to perform with endurance and to run
to perform with endurance and run

OA B, IMO C

also dunnot understand why B is correct... and ...and...

Okay. The big battle is between B and C.

The only way in which C would have been correct is if there were a comma before running. Since this is not the case, we can safely say that C is not right.

As for the justification of B, performing with endurance and running swiftly even late in match are not independent but related to each other. running swiftly even late in match qualifies performing with endurance. So an and before running is justified. The final and just ends the list.

The following things are parallel -
- serving with speed and accuracy
- performing with endurance and running swiftly even late in match
and,
- defending against tricky drop shots and lobs

You can make the case that and does not necessarily show the relation very well but I don't see a better way out.