A slab of dielectric constant $\mathrm{K}$ has the same cross-sectional area as the plates of a parallel plate capacitor and thickness $\frac{3}{4} \mathrm{~d}$, where $\mathrm{d}$ is the separation of the plates. The capacitance of the capacitor when the slab is inserted between the plates will be :

(Given $\mathrm{C}_{0}$ = capacitance of capacitor with air as medium between plates.)

1. A $\frac{4 K C_{0}}{3+K}$ Correct answer
2. B $\frac{3 K C_{0}}{3+K}$
3. C $\frac{3+K}{4 K C_{0}}$
4. D $\frac{K}{4+K}$