Consider the following statements regarding heavy water $(D_2O)$. Which of the following statements is/are correct?
$(A)$ Heavy water is used as a moderator in nuclear reactors.
$(B)$ The power of association is higher in $D_2O$ than in ordinary water $(H_2O)$.
$(C)$ Heavy water is more effective as a solvent than ordinary water.

• A
  $A$ and $C$
• B
  $A$ and $B$
• C
  $A, B$ and $C$
• D
  $B$ and $C$