b
If a dielectric slab of dielectric constant \(K\) is filled in between the plates of a capacitor after charging the capacitor (i.e., after removing the connection of battery with the plates of capacitor) the potential difference between the plates reduces to \(\frac {1}{K}\) times and the potential energy of capacitor reduces to \(\frac {1}{K}\) times but there is no change in the charge on the plates.