A parallel plate capacitor with air as a dielectric has capacitance C. A slab of dielectric constant K, having same thickness as the separation between the plates is introduced so as to fill one fourth of the capacitor as shown in the figure. The new capacitance will be
(a) (K + 3) C/4
(b) (K + 2) C/4
(c) (K + 1) C/4
(d) KC/4