$A$ parallel plate capacitor is charged to a potential difference of $100\,V$ and disconnected from the source of $emf$. $A$ slab of dielectric is then inserted between the plates. Which of the following three quantities change?
$(i)$ The potential difference
$(ii)$ The capacitance
$(iii)$ The charge on the plates

• A
  only $(i)$ and $(ii)$
• B
  only $(i)$ and $(iii)$
• C
  only $(ii)$ and $(iii)$
• D
  All $(i), (ii)$ and $(iii)$