Which of the following is not associated with water molecules?

• A
  $Cryolite$ $(Na_3AlF_6)$
• B
  $Bauxite$ $(Al_2O_3 \cdot 2H_2O)$
• C
  $Kernite$ $(Na_2B_4O_7 \cdot 4H_2O)$
• D
  $Borax$ $(Na_2B_4O_7 \cdot 10H_2O)$