A parallel plate capacitor has the space between its plates filled by two slabs of thickness $(\mathrm{d} / 2)$ each and dielectric constant $\mathrm{K}_{1}$ and $\mathrm{K}_{2}$ If $\mathrm{d}$ is the plate separation of the capacitor, then capacity of the capacitor is ..........
(A) $\left[\left(2 \mathrm{~d} \in_{0}\right) / \mathrm{A}\right]\left[\left(\mathrm{K}_{1}+\mathrm{K}_{2}\right) /\left(\mathrm{K}_{1} \mathrm{~K}_{2}\right)\right]$
(B) $\left[\left(2 \mathrm{~A} \in_{0}\right) / \mathrm{d}\right]\left[\left(\mathrm{K}_{1} \mathrm{~K}_{2}\right) /\left(\mathrm{K}_{1}+\mathrm{K}_{2}\right)\right]$
(C) $\left[\left(2 \mathrm{Ad} \epsilon_{0}\right) / \mathrm{d}\right]\left[\left(\mathrm{K}_{1}+\mathrm{K}_{2}\right) /\left(\mathrm{K}_{1} \mathrm{~K}_{2}\right)\right]$
d] $\left(K_{1}+K_{2}\right)$
(D) $\left[\left(2 \mathrm{~A} \in_{0}\right) /\right.$