If a parallel plate capacitor has a 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 of C'/C will be;
{A} K/2(K+1)
{B} 2K/(K+1)
{c}5k/(4k+1)
{d} 4k/(3k+1)
