31. The capacitance of a parallel plate capacitor with air as dielectric is C. If a slab of dielectric constant 
K and of the same thickness as the separation between the plates is introduced so as to fill 1/4^th of the 
capacitor (shown in figure), then the new capacitance is 


$$\begin{gathered} \left(a\right) (K+2)\frac{C}{4} \\ \left(b\right) (K+3) \frac{C}{4} \\ \left(c\right) (K+1) \frac{C}{4} \\ \left(d\right) None of these \end{gathered}$$