The halides of alkaline earth metals form hydrates such as $MgCl_2 \cdot 6H_2O$,$CaCl_2 \cdot 6H_2O$,$BaCl_2 \cdot 2H_2O$,and $SrCl_2 \cdot 2H_2O$. What does this indicate about the halides of group $2$ elements?

• A
  They are hygroscopic in nature.
• B
  They act as dehydrating agents.
• C
  They can absorb moisture from the air.
• D
  All of the above.