A parallel plate air capacitor is fully charged and then the battery is removed. A dielectric slab is now put between the plates. Which of the following statements is correct?

The charge on the plates does not change, the potential difference between the plates decreases and the energy stored also decreases

The charge on the plates decreases

The charge on the plates does not change, the potential difference between the plates increases and the energy stored also increases

The charge on the plates does not change, but the potential difference increases