The correct statement regarding the halides and monoxides of the alkaline earth metals is:

• A

  All the oxides and halides are ionic in nature.
• B

  All the halides are always monomeric.
• C

  Hydrated chlorides of all the alkaline earth metals give dehydrated products at high temperature.
• Correct answer
  D

  Beryllium monoxide reacts with water to give beryllium hydroxide which further reacts with an alkali metal hydroxide to give $\left[\mathrm{Be}(\mathrm{OH})_4\right]^{2-}$.

Hence, the correct answer is option: 'D'.