Which of the following statement/s is/are correct

a) The dielectric constant of D₂O is slightly less than that of H₂O. Therefore, ionic compounds are less soluble in D₂O than H₂O
b) The Density of water is maximum at $4^{\circ }\mathrm{C}.$The Density of D₂O is maximum at ${11}^{\circ }\mathrm{C}.$
c) Deuterium compound, can be prepared by exchange reaction where deuterium is exchanges for hydrogen under suitable conditions