If a parallel plate capacitor has capacity C, on inserting a dielectric slab of relative permeability K and thickness equal to one fourth of the plate separation is placed between the plates, then its capacity becomes C'.the value if C'/C will be;
(A) K/2(K+1)
(B) 2K/(K+1)
(C) 5K/(4K+1)
(D)4K/(3K+1) PLEASE ALSO GIVE EXPLANATION