I am confused between A and C

D and E are out as Each ahs to use singular verb and one of them use " are " the other changes meaning by using "Seen"

Both the sides is wordy so B is out

I would go with A

I think answer is A as whenever is singular subject and would regquire either side

let us try to form a simpler version of the correct sentence:
Whenever X is sought to be created through Y, the effort is attacked by forces on both sides
or
Whenever X is sought to be created through Y, the effort is attacked by force on either side

Nearest form to one of the above correct forms is C

OA please

I would like to go with A.
"created through"

would go for C

i like C better due to the use of the comma. "whenever some sort..." is an adverb phrase which modifies "it is attacked..." so a comma makes sense

A. no comma. either side changes the meaning, leaves open the possibility that one side may support. use of "through"

B. no comma, both the sides is wordier than both sides. use of "through"

C. uses comma. the use of "by" makes the subject clear- ie a group, track-2 diplomacy. "it" refers back to this track 2 diplomacy. the use of "through" makes the subject ambiguous.

D. . no comma. use of seen is weird. use of "through"

E. either side changes the meaning, leaves open the possibility that one side may support. use of "through"

OA is A

Can somone explain what's wrong with C.