Correct choice is (c) [(V-Vc)/γm0] ≤ Fqd
For explanation I would say: Stiffeners not subjected to external loads or moments should be checked for buckling for a force Fd = [(V-Vc)/γm0] ≤ Fqd, where Fqd is design resistance of intermediate stiffeners, V is factored shear force adjacent to the stiffener, Vcr is shear buckling resistance of the web panel designed without using tension field action. This check is required for intermediate stiffeners only when tension field action is utilized in webs.