A slab of material of dielectric constant k, having the same area as the plate of a parallel plate capacitor but has a thickness $\frac{3}{5}$ of the distance between the plates d, is inserted between the plates of the capacitor. When there is air between the plates, the potential difference is $V_0$. What is the potential difference between the plates of the capacitor after inserting the dielectric?

$\left(\frac{2 k+3}{5 k}\right) V_0$

The correct answer is Option (2) → $\left(\frac{2 k+3}{5 k}\right) V_0$