Sentence Correction (SC) | Re: Unlike the virginal, whose single set of strings runs parallel to the

Hiegmat ,EMPOWERgmatVerbal

I am confused here.
In Option (A) single set of strings runs --> isnt this correct?
Single set is singular as we can interprete it as 1 set (not 2 set / 3 set then plural)
so For Single set runs Verbmatches